EnviroESCA

Using the nascent band theory of solids, Cabrera and Mott designed in the late 1940s a model for the low-temperature oxidation of metals that still stands today as a landmark. The core assumption is that an electric field set up in the growing oxide at thermodynamic equilibrium drives the transport of the ionic species responsible for the oxidation process. The existence of an electrostatic potential has long been sought experimentally by in situ measurement of the work function changes in the presence of gaseous O₂. Here, we demonstrate that the work function measurement is insufficient to test the model. Instead, the oxide band structure characteristics (surface dipole energy barrier and band bending) should be followed. We exemplify this for the paradigmatic case of the Al(111) surface oxidation at room temperature using near-ambient pressure X-ray photoemission spectroscopy (operated up to a pressure of 1 mbar). Using an in situ spectroscopic tool, we monitor the oxide growth in real time and obtain detailed energetic information on the metal/oxide/gas system. This allows us to validate the central hypothesis of the Cabrera–Mott model (i.e., the existence of the Cabrera–Mott potential). The original assumption that oxygen anions are adsorbed at the oxide/gas interface is also discussed. The concept of “realistic conditions” also means that the issue of water coadsorption (inherent to near-ambient O₂ conditions) is addressed. The specific consequences of the Cabrera–Mott regime of oxidation are also discussed with respect to the functioning of aluminum-based superconducting qubits. The in situ, real-time spectroscopic methodology used here is effective and can be generalized far beyond the specific case of aluminum oxidation.
 

Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.

Ionizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

Interfacially confined microenvironments have recently gained attention in catalysis, as they can be used to modulate reaction chemistry. The emergence of a 2D nanospace at the interface between a 2D material and its support can promote varying kinetic and energetic schemes based on molecular level confinement effects imposed in this reduced volume. We report on the use of a 2D oxide cover, bilayer silica, on catalytically active Pd(111) undergoing the CO oxidation reaction. We “uncover” mechanistic insights about the structure‐activity relationship with and without a 2D silica overlayer using in situ IR and X‐ray spectroscopy and mass spectrometry methods. We find that the CO oxidation reaction on Pd(111) benefits from confinement effects imposed on surface adsorbates under 2D silica. This interaction results in a lower and more dispersed coverage of CO adsorbates with restricted CO adsorption geometries, which promote oxygen adsorption and lay the foundation for the formation of a reactive surface oxide that produces higher CO 2 formation rates than Pd alone.

Interfacially confined microenvironments have recently gained attention in catalysis, as they can be used to modulate reaction chemistry. The emergence of a 2D nanospace at the interface between a 2D material and its support can promote varying kinetic and energetic schemes based on molecular level confinement effects imposed in this reduced volume. We report on the use of a 2D oxide cover, bilayer silica, on catalytically active Pd(111) undergoing the CO oxidation reaction. We “uncover” mechanistic insights about the structure‐activity relationship with and without a 2D silica overlayer using in situ IR and X‐ray spectroscopy and mass spectrometry methods. We find that the CO oxidation reaction on Pd(111) benefits from confinement effects imposed on surface adsorbates under 2D silica. This interaction results in a lower and more dispersed coverage of CO adsorbates with restricted CO adsorption geometries, which promote oxygen adsorption and lay the foundation for the formation of a reactive surface oxide that produces higher CO 2 formation rates than Pd alone.

Surface-supported metal-organic frameworks HKUST-1 (Hong Kong University of Science and Technology) were used as a model system for a development of a near ambient pressure (NAP) XPS based approach to investigate interaction with atmospheres of water, methanol or pyridine at pressures ranging from 1 to 4 mbar. The films were grown on a gold substrate functionalized with a COOH-terminated self-assembled monolayer using liquid-phase epitaxy in a step-by-step fashion. Measurement protocols were developed and optimised for different gases in order to obtain spectra of similar quality in terms of signal intensity, noise and shape. Peak shapes were found to depend on the efficiency of charge compensation. Reference measurements in argon proved to be a useful strategy not only for the evaluation of the Cu(II)-fraction in pristine samples, but also to identify the contributions by the respective gas atmosphere to the C 1s and O 1s photoelectron spectra. Reduced copper was found during the exposition of HKUST-1 to water vapour and pyridine, but this effect was not observed in case of methanol. Additionally, it was established that there are no changes in relative Cu(II) percentage with increasing exposure time. This indicates that saturation was reached already at the lowest time of gas exposure. A detailed elucidation of the mechanism of Cu(II) reduction to Cu(I) in HKUST-1 mediated by water and pyridine is part of ongoing work and not in the scope of the present paper.

In this topical review we catagorise all ambient pressure x-ray photoelectron spectroscopy
publications that have appeared between the 1970s and the end of 2018 according to their
scientific field. We find that catalysis, surface science and materials science are predominant,
while, for example, electrocatalysis and thin film growth are emerging. All catalysis
publications that we could identify are cited, and selected case stories with increasing
complexity in terms of surface structure or chemical reaction are discussed. For thin film
growth we discuss recent examples from chemical vapour deposition and atomic layer
deposition. Finally, we also discuss current frontiers of ambient pressure x-ray photoelectron
spectroscopy research, indicating some directions of future development of the field.
Keywords: ambient pressure x-ray photoelectron spectroscopy, synchrotron radiation,
catalysis, atomic layer deposition, chemical vapour deposition, operando

In this article, we present Near Ambient Pressure (NAP)-X-ray Photoelectron Spectroscopy (XPS) results from model and commercial liquid electrolytes for lithium-ion battery production using an automated laboratory NAP-XPS system. The electrolyte solutions were (i) LiPF₆ in EC/DMC (LP30) as a typical commercial battery electrolyte and (ii) LiTFSI in PC as a model electrolyte. We analyzed the LP30 electrolyte solution, first in its vapor and liquid phase to compare individual core-level spectra. In a second step, we immersed a V₂O₅ crystal as a model cathode material in this LiPF₆ solution. Additionally, the LiTFSI electrolyte model system was studied to compare and verify our findings with previous NAP-XPS data. Photoelectron spectra recorded at pressures of 2–10 mbar show significant chemical differences for the different lithium-based electrolytes. We show the enormous potential of laboratory NAP-XPS instruments for investigations of solid-liquid interfaces in electrochemical energy storage systems at elevated pressures and illustrate the simplicity and ease of the used experimental setup (EnviroESCA).

Dry reforming of methane (DRM) involves the conversion of CO₂ and CH₄, the most important greenhouse gases, into syngas, a stoichiometric mixture of H₂ and CO that can be further processed via Fischer–Tropsch chemistry into a wide variety of products. However, the devolvement of the coke resistant catalyst, especially at high pressures, is still hampering commercial applications. One of the relatively new approaches for the synthesis of metal nanoparticle based catalysts comprises the use of metal-organic frameworks (MOFs) as catalyst precursors. In this work we have explored MOF-74/CPO-27 MOFs as precursors for the synthesis of Ni, Co and bimetallic Ni-Co metal nanoparticles. Our results show that the bimetallic system produced through pyrolysis of a Ni-Co@CMOF-74 precursor displays the best activity at moderate pressures, with stable performance during at least 10 h at 700 °C, 5 bar and 33 L·h⁻¹·g⁻¹.

Near ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 5000 Pa. With NAP-XPS, liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly can be studied. In this submission, we show survey, C 1s, Br 3p, and Br 3d NAP-XPS spectra of 1-bromonaphthalene. Small O 1s and N 1s signals from background gas (N₂ and air) are also observed.

The oxides, hydroxides, and oxo-hydroxides of iron belong to the most abundant materials on earth. They also feature a wide range of practical applications. In many environments, they can undergo facile phase transformations and crystallization processes. Water appears to play a critical role in many of these processes. Despite numerous attempts, the role of water has not been fully revealed yet. We present a new approach to study the influence of water in the crystallization and phase transformations of iron oxides. The approach employs model-type iron oxide films that comprise a defined homogeneous nanostructure. The films are exposed to air containing different amounts of water reaching up to pressures of 10 bar. Ex situ analysis via scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and X-ray diffraction is combined with operando near-ambient pressure X-ray photoelectron spectroscopy to follow water-induced changes in hematite and ferrihydrite. Water proves to be critical for the nucleation of hematite domains in ferrihydrite, the resulting crystallite orientation, and the underlying crystallization mechanism.

Near-ambient-pressure x-ray photoelectron spectroscopy (NAP-XPS) and x-ray-induced Auger electron spectroscopy were used to characterize gas-phase carbon monoxide, CO(g). In this submission, the authors show the survey, valence band, O 1s, C 1s, O KLL Auger, and C KLL Auger spectra acquired using high-resolution synchrotron NAP-XPS with a photon energy of 647.08 eV.

Near-ambient pressure XPS (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500 Pa or greater. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s and survey NAP-XPS spectra from 1,4-polymyrcene. The C 1s and O 1s envelopes are fit with Gaussian-Lorentzian product, asymmetric Lorentzian, and Gaussian-Lorentzian sum functions, respectively. Water vapor and argon are used to control sample charging, and the corresponding signals from the gases are present in the survey spectra. The effect of background gas pressure on photoelectron attenuation is illustrated with a sample of polytetrafluoroethylene.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, C 1s, and O 1s NAP-XPS spectra of polyethylene terephthalate, a common, widely used thermoplastic. The C 1s envelope was fit with different approaches, i.e., to three, four, and five Gaussian–Lorentzian sum (GLS) functions. Hartree–Fock orbital energy calculations of a model trimer served as a guide to an additional fit of the C 1s envelope. The best fit was obtained by adding an extra component to the four-component fit to compensate for adventitious carbon or additives in the polymer. The O 1s signal was well fit with two GLS peaks with a 1:1 area ratio representing the C—O and C=O moieties in PET.

Near ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, O 1s/Ag 3p, Ca 3p/Ag 3d, and extended valence band (0–130 eV) NAP-XPS spectra of an ancient Roman coin at three different positions. A small N 1s signal from N₂ background gas is also observed. On the obverse side, the coin bears the bust of Licinius I. On the reverse side, it bears the image of Jupiter. The Ag 3d region indicates different amounts of silver at different oxidation states in different positions.

Hydrothermal carbonisation (HTC) has been demonstrated to be a sustainable thermochemical process,
capable of producing functionalised carbon materials for a wide range of applications. In order to better
apply such materials, the local chemistry and reaction pathways governing hydrothermal carbon growth
must be understood. We report the use of scanning transmission X-ray microscopy (STXM) to observe
chemical changes in the functionality of carbon between the interface and bulk regions of HTC. Spatiallyresolved,
element-specific X-ray photo-absorption spectra show the presence of differing local carbon
chemistry between bulk “core” and interface “shell” regions of a glucose-derived hydrothermal carbon
spherule. STXM provides direct evidence to suggest that mechanistic pathways differ between the core
and shell of the hydrothermal carbon. In the shell region, at the water-carbon interface, more aldehyde
and/or carboxylic species are suspected to provide a reactive interface for bridging reactions to occur
with local furan-based monomers. In contrast, condensation reactions appear to dominate in the core,
removing aryl-linking units between polyfuranic domains. The application of STXM to HTC presents
opportunities for a more comprehensive understanding of the spatial distribution of carbon species
within hydrothermal carbon, especially at the solvent-carbon interface.

In this paper, we present for the first time the obtaining and characterization of new antibacterial and biocompatible nano-ZnO–bacterial cellulose (BC) material with controlled interfaces for studying in vitro microorganisms (Escherichia Coli (ATCC 8737), B. subtilis Spizizenii Nakamura (ATCC 6633), Candida albicans (ATCC10231)) and mammalian cells (human dermal fibroblast cells) response. The use of BC based material with controlled characteristics in terms of quantity and distribution of ZnO onto BC membrane (with 2D and 3D fibers arrangement) is directly correlated with the surface chemical and topographical properties, the method of preparation, and also with the type of cells implied for the specific application within the bioengineering fields. In our study, the uniform distribution and the control on the quantity of ZnO nanoparticles onto 3D BC were obtained using matrix assisted pulsed laser evaporation (MAPLE) method. The influence on particle distribution onto 3D bio cellulose were investigated based on two types of solvents (water and chloroform) involved in target preparation within MAPLE deposition. The attachment of the nanoparticles to the bacterial cellulose surface and fibrils was demonstrated by SEM and FT-IR studies. The BC-ZnO showed both resistance to bacteria-sticking and non-cytotoxic effect on the human dermal fibroblasts cells at a mass distribution onto surface of 1.68 µg ZnO NPS/mm². These results represent a good premise in terms of tailoring BC substrates with ZnO particles that could determine or enhance both the biocompatibility and antibacterial properties of BC-composite materials.

The production of furfuryl alcohol from furfural hydrogenation in gas
phase is of great significance for the valorization of biomass. The existing catalyst for
this transformation suffers from high cost and complex preparation process. Thus, a
highly efficient copper catalyst was developed by a simple impregnation method
using ethanolamine modified granular silica as carrier.
The catalytic performance was related to the amount of ethanolamine used in modification.
Highly dispersed copper with uniform particle size distribution was obtained from appropriate amount of
ethanolamine modified granular silica. The ethanolamine modified granular silica
(mass ratio between ethanolamine and silica was 3 in the initial modification mixture)
supported copper catalyst exhibited the best performance in terms of catalyst lifetime
thanks to its maximum amount of Cu⁰ sites and largest amount of Cu⁺ sites. A slow
deactivation of the catalyst after extended time on stream evaluation is attributed to
carbon deposition and slow copper sintering.

Modulating electronic structure of graphene overlayers is highly demanding for its potential applications in
microelectronics, sensors, and catalysis, which however remains a grand challenge. Here, we report electrochemistry-
involved treatments to tune the electronic structure of graphene overlayers. Both galvanic corrosion
and potential-aided intercalation of H₂O were employed to change the graphene/Cu interfaces to graphene/
Cu₂O/Cu and graphene/H₂O/Cu interfaces, respectively. Electronic properties and structural changes of the
graphene/Cu interfaces were investigated by X-ray photoelectron spectroscopy, in-situ Raman, and atomic force
microscopy. The formed Cu₂O interlayer blocks the charge transfer between graphene overlayer and Cu substrate,
which turns n-type doping of the as-grown graphene to free-standing state. In contrast, the intercalated
H₂O interlayer induces much stronger n-type doping in graphene through the electrostatic field effect generated
by confined H₂O. This work offers efficient but mild methods to modulate the doping state of graphene layers.

Near ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this paper, we show the NAP-XPS survey; O 1s, Ca 2p, C 1s, K 2p, Al 2s, Al 2p, Si 2p, and Si 2s narrow scans; and the extended valence band spectrum of clinoptilolite, a natural zeolite that would be difficult to analyze by conventional XPS. A small N 1s signal from N₂(g) is also observed in the survey spectrum. Signals in the narrow scans are fit to Gaussian–Lorentzian sum and Gaussian–Lorentzian product functions.

Near-ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Here, we show the NAP-XPS analysis of untreated/blank human hair, and human hair that has been colored (red) and treated with a commercial conditioner, or bleached and treated with a different conditioner. Survey spectra are shown of each material along with figures comparing their Si 2p, S 2p, and C 1s spectra. The survey spectrum of untreated hair shows S 2p, S 2s, C 1s, Ca 2p, N 1s, and O 1s peaks and corresponding O, N, and C Auger signals. The survey spectra of the colored and bleached hair show significant Si 2s and Si 2p signals and reduced or eliminated S 2p and S 2s peaks, presumably due to the deposition of dimethicone (polydimethylsiloxane) from the corresponding commercial hair treatment products. Narrow scans similarly indicate the deposition of a silicon-containing material on the two types of treated hair, with a concomitant decrease in the intensity of the sulfur signals from the hair. Upon treatment, the C 1s envelope also changes—the chemically shifted peak attributable to amide-type carbon disappears.

Liquid jet X-ray photoelectron spectroscopy is used under near ambient pressure conditions to characterize Fe²⁺ aqueous solutions. Counter ions, such as Cl⁻ and Br⁻ ions, added to the solution lead to changes in the first solvation sphere of the Fe-aqua complex in solution. Binding energy shifts of 0.4 eV to lower binding energy are observed in the Cl 2p spectra, 2 eV to higher binding energy in the Fe 2p spectra and no shifts are observed in the Br 3d spectra. Depletion of the Cl⁻ species is observed at the interface,
caused by coordination with Fe². Depletion of Cl⁻ at the liquid/vapor interface may have significant impacts on oxidative chemistry at the interface of atmospheric aerosols that contain both chloride and iron. The Cl⁻ complexation with the Fe²⁺ ions will also affect the Fenton chemistry that is dependent on this metal ion.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa, or even higher in some cases. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS survey and narrow scans from nitrogen gas (N2), a material that could not be analyzed at moderate pressures by conventional approaches. Nitrogen gas is an important reference material for NAP-XPS because residual N2 from the air and/or venting produces an N 1s signal in many NAP-XPS spectra. Nitrogen gas may also be deliberately employed as the gaseous background for NAP-XPS experiments. The survey spectrum of N2 gas contains N 1s, N 2s, N KLL (Auger), and valence band signals. This submission is part of a series of articles on NAP-XPS that has been submitted to Surface Science Spectra.

This study aimed to obtain possible materials for future antimicrobial food packaging applications based on biodegradable bacterial cellulose (BC). BC is a fermentation product obtained by Gluconacetobacter xylinum using food or agricultural wastes as substrate. In this work we investigated the synergistic effect of zinc oxide nanoparticles (ZnO NPs) and propolis extracts deposited on BC. ZnO NPs were generated in the presence of ultrasounds directly on the surface of BC films. The BC-ZnO composites were further impregnated with ethanolic propolis extracts (EEP) with different concentrations.The composition of raw propolis and EEP were previously determined by gas-chromatography mass-spectrometry (GC-MS), while the antioxidant activity was evaluated by TEAC (Trolox equivalent antioxidant capacity). The analysis methods performed on BC-ZnO composites such as scanning electron microscopy (SEM), thermo-gravimetrically analysis (TGA), and energy-dispersive X-ray spectroscopy (EDX) proved that ZnO NPs were formed and embedded in the whole structure of BC films. The BC-ZnO-propolis films were characterized by SEM and X-ray photon spectroscopy (XPS) in order to investigate the surface modifications. The antimicrobial synergistic effect of the BC-ZnO-propolis films were evaluated against Escherichia coli, Bacillus subtilis, and Candida albicans. The experimental results revealed that BC-ZnO had no influence on Gram-negative and eukaryotic cells.

Furfuryl alcohol, a vital intermediate for the production of foundry resins, fragrances, pharmaceuticals and
pesticide, is produced by hydrogenation of furfural in gas phase or liquid phase. The furfuryl alcohol production
in gas phase over silica supported copper catalyst is favored thanks to the environmental and technical advantages.
The effect of preparation methods of silica supported copper catalysts on the structure and performance
was investigated by means of ICP, N₂ physisorption, ex-situ/in-situ XRD, in-situ XPS, FT-IR, H₂-TPR, TEM,
N₂O titration, TG as well as furfural hydrogenation. The results indicated that the different catalyst synthesis
strategies led to the diverse copper species in the calcined samples and disparate Cu⁰ surface area as well as
different molar ratio of Cu⁺/(Cu⁺+Cu⁰) in the fresh samples. The performance of impregnation derived
sample was poorer than that of commercial CuCr-Strem catalyst. The catalysts prepared by deposition precipitation
and ion exchange exhibited similar performance to the CuCr-Strem. The ammonia evaporation derived
catalyst (Cu/SiO₂-EA) showed superior performance in the activity, selectivity and stability among all the studied
catalysts. The excellent performance was related to the highest surface area of Cu⁰, smallest copper particle
size, large surface area and pore volume as well as appropriate higher Cu⁺/(Cu⁺+Cu⁰) ratio. Furthermore, all
the copper catalysts went through deactivation, which was caused by carbon deposition, during the reaction.
Owing to the largest amount of Cu⁰ sites and large SBET, the Cu/SiO₂-EA exhibited the slowest deactivation rate.

Bulk ZrO₂ has shown high activity and selectivity for propane dehydrogenation (PDH). Its catalytic performance
can be enhanced by substitution of the Zr ions with suitable dopant ions. In this study, a series of Cu-doped ZrO₂
metal oxides (CuZrO-x) have been prepared using the co-precipitation method and the effects of the amount of
dopant on their properties have been investigated. The appropriate amount of Cu dopant promotes the creation
of oxygen vacancies and coordinatively unsaturated Zr_cus⁴⁺ sites, active sites for PDH; however, excess Cu forms
bulk CuO in the CuZrO-x catalysts resulting in decreased activity. The catalytic activity for PDH is closely
correlated to the amount of weak Lewis acid sites in CuZrO-x. Moreover, a comparison of the CuZrO-x properties
with those of Cu-impregnated ZrO₂ has shown that the amount of acid sites and therefore, the catalytic performance,
depends on the doping method.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less-traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa, or even higher in some cases. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, the authors show NAP-XPS survey spectra, and C 1s and O 1s narrow scans of two samples of paper (a white office paper and the nonsticky side of a yellow post-it note). The white office paper was analyzed at three specific positions: an unprinted portion, a light blue letter, and a dark blue letter in the “SPECS” logo. Survey spectra show the presence of carbon, oxygen, nitrogen, and calcium in all the samples. The yellow paper shows a small amount of silicon. Fits to the C 1s and O 1s regions are shown. The O 1s narrow scans are fit with four peaks using a literature approach previously employed for paper and with three peaks in a more ad hoc fashion. The latter approach yields better fits.

Although graphite-like carbon (GLC) films have been used to protect the engineering components due to their
high mechanical properties and low friction coefficients, the poor interfacial bonding strength and high internal
stress can lead their rapid failure. In this study, the bias-gradient (30–120 V) as well as the usual constant bias
protocols (30, 60 and 120 V) has been adopted to deposit the GLC films on 316 L stainless steel and silicon using
unbalanced magnetron sputtering technology. Based upon the microstructure and composition analysis by SEM,
AFM, XRD, Raman and XPS, the sp³ content and compactness of the films are increased with the increase of the
deposition bias. Compared to the film at the constant bias of 120 V, the bias-graded film has a comparable
hardness but superior adhesive strength. Detailed fretting wear testing under ambient air and dry N₂ atmospheres
against 25mm diameter Si₃N₄ ball has been carried out. The friction curves disclosed a three-stage
evolution feature: the surface working area, the interlayer transition area and the coating failure area. The biasgraded
film displayed the lowest friction coefficient and the longest fatigue life. Further the fretting mechanisms
at different stages have been elaborated in terms of the chemical composition, microstructure and mechanical
properties.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. In this study, poly(γ-benzyl L-glutamate) (PBLG) with a molar mass of 11.3 kg/mol was analyzed by NAP-XPS; here, we show the survey, C 1s, N 1s, and O 1s narrow scans of PBLG. The C 1s peak envelope was fitted in three different ways, to five, six, or seven synthetic peaks. In each fit, there was also a shake-up signal. The O 1s narrow scan was well fit with three peaks: C—O and C=O in a 1:2 ratio from the polymer, and a higher energy signal from water vapor. Hartree–Fock orbital energies of a model monomer served as a guide to an additional fit of the C 1s envelope.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., up to 2500 Pa, or higher in some cases. NAP-XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we present NAP-XPS C 1s and O 1s narrow scans and a survey spectrum of a coffee bean, a material that would be difficult or even impossible to analyze by conventional XPS. Coffee beans are ground to produce coffee powder, which is the source of one of the world’s most common beverages, coffee. The survey spectrum shows small amounts of sulfur and calcium.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show C 1s, O 1s, and survey NAP-XPS spectra from ethylene glycol, an organic solvent that could not be analyzed at near-ambient pressures by conventional approaches. An N 1s signal is present in the survey spectrum of the material.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500 Pa or higher. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Because of the relatively high working pressure of NAP-XPS, the components of ambient air may be present in the analytical chamber during data acquisition. In this submission, we show survey, O 1s, N 1s, valence band, oxygen Auger (KLL), and nitrogen Auger (KLL) NAP-XPS spectra from ambient air, a material that could not be analyzed at moderate pressures by conventional XPS.

Near-ambient pressure–x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, 2s, 2p, 3s, 3p, and the Auger LMM NAP-XPS spectra from argon gas, a material that could not be analyzed at moderate pressures by conventional methods. A small N 1s signal from residual nitrogen gas in the chamber is also present in the survey spectrum.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can be used to probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey and O 1s NAP-XPS spectra from water vapor, a material that could not be analyzed at moderate pressures by conventional approaches and that is expected to be present in many analyses.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can analyze moderately volatile liquids, biological samples, porous materials, minerals, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS survey and Ca 2p, O 1s, and C 1s narrow scans from calcite, which was analyzed here without external charge compensation. Quantitation of the peaks in the narrow scan gives a ratio that is very close to the theoretical 1:1:3 ratio expected for Ca:C:O in the material. The small N 1s signal in the survey spectrum is attributed to residual nitrogen gas in the analysis chamber.

Near-ambient pressure–x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Polytetrafluoroethylene (PTFE) is an important polymer with many applications in science and industry. It is an insulator that charges under x-ray illumination at high vacuum. In this submission, we show NAP-XPS spectra of PTFE. Survey spectra are shown at different background gas (air) pressures. These spectra contain F 2s, C 1s, O 1s, N 1s, F 1s, and F Auger signals. Also presented are F 1s narrow scans over a range of background pressures and illumination times. Peaks decrease in width, shift toward literature values, and improve in shape with increasing background gas pressure.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, C 1s, O 1s, and N 1s narrow scans from an aqueous solution of a common protein, bovine serum albumin. The C 1s peak envelope is well fit to four symmetric peaks of equal width that correspond to carbon bonded to carbon and hydrogen (C-1), carbon singly bonded to oxygen (C-2), carbonyl and/or amide carbon (C-3), and carboxyl carbon (C-4). Two possible peak fits are considered for the N 1s and O 1s peak envelopes. The N 1s signal is fit to four peaks that correspond to amine (—NH₂), amide (O˭C‒NH₂), ammonium (—NH₃⁺), and N₂(g) nitrogen, and alternatively to three peaks that correspond to amine, amide, and N₂(g) nitrogen. The O 1s peak envelope is similarly fit to three and four components.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, a wide variety of unconventional materials can be analyzed, including moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. Charge compensation with NAP-XPS takes place simply through the residual/background gas in the chamber, which is ionized by the incident x-rays. High quality spectra—high resolution and good signal-to-noise ratios—are regularly obtained. This article is an introduction to a series of papers in Surface Science Spectra on the NAP-XPS characterization of a series of materials. The purpose of these articles is to introduce and demonstrate the versatility and usefulness of the technique.

Near-ambient pressure–x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa, or even higher in some cases. With NAP-XPS, XPS can probe particles, moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, narrow (Zr 3p, Zr 3d, and O 1s), and Auger (O KLL) NAP-XPS scans of ZrO₂ particles. Charge compensation for this insulating sample took place via the residual gas in the chamber. Zirconia is an important ceramic material. Accordingly, the XPS spectra of zirconia should be useful references.

Near ambient pressure - x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at 2500 Pa or higher. With NAP-XPS, one can analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission we show C 1s, O 1s, and survey NAP-XPS spectra from poly(_L-lactic acid). The C 1s and O 1s envelopes were fit with three and two Gaussian-Lorentzian sum functions, respectively. Water vapor (800 Pa) was used as the residual gas for charge compensation, which was confirmed by the sharp peak at 535.0 eV in the O 1s narrow scan. The uniqueness plot corresponding to the C 1s fit shows that the fit parameters had statistical significance. C 1s and O 1s spectra of PLLA damaged by exposure to x-rays for ca. 1 hour are also included.

Near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa, or higher in some cases. With NAP-XPS, XPS can be used to analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, O 1s, O KLL, and valence band NAP-XPS spectra from liquid water, a material that could not be analyzed at moderate pressures by conventional approaches. The O 1s signal was fit to two components attributed to liquid and vapor phase water. The carbon in the survey spectrum is attributed to contaminants in the water and/or adventitious carbon.

Near ambient pressure-x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at ca. 2500 Pa, or higher in some cases. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show an NAP-XPS survey spectrum, and also O 1s and C 1s narrow scans, of a commercial soft drink, Coca-Cola. Clearly this is a material that could not be analyzed at moderate pressures by conventional XPS. The C 1s narrow scan is fit to five synthetic components. The O 1s narrow scan shows strong contributions from both liquid and gas phase water. A small N 1s signal in the survey spectrum is attributed to background nitrogen. The shape of the uniqueness plot corresponding to the C 1s fit suggests that the fit parameters are statistically significant.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show the survey, O 1s, C 1s, valence band, O KLL Auger, and C KLL Auger NAP-XPS spectra of gaseous carbon dioxide, CO₂, a material that would be difficult to analyze by conventional XPS. A small N 1s signal from N₂(g) is also observed in the survey spectrum. The C 1s and O 1s signals in the narrow scans are fit to Gaussian–Lorentzian sum and asymmetric Lorentzian (LA) functions. Better fits are obtained with the LA synthetic line shape. Since it is likely that CO₂(g) will be present in other NAP-XPS analyses, these data should serve as a useful reference for other researchers.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show survey, O 1s, C 1s, S 2p, and S 2s NAP-XPS spectra from dimethyl sulfoxide (DMSO), a widely used organic solvent that is miscible with water. The sample was analyzed directly in its native, liquid state at room temperature. In general, both liquid and gas phase peaks are observed in the narrow scans. Due to the importance of DMSO in both chemistry and biology, it is likely that it will appear in future NAP-XPS analyses. Accordingly, these data may serve as a reference for future work.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show the survey, O 1s, valence band, and O KLL Auger NAP-XPS spectra of oxygen gas, O2, a material that would be difficult to analyze by conventional XPS. A small N 1s signal from N₂(g) is also observed in the survey spectrum. The O 1s narrow scan is fit to Gaussian-Lorentzian sum functions. The Lorentzian character of this synthetic line shape was varied to obtain the best fit. Since it is likely that O₂(g) will be present in other NAP-XPS analyses, these data should serve as a useful reference for other researchers.

Liquid phase adsorption is a common technique in waste water purification. However, this process has some downsides. The removal of environmentally harmful contaminants from organic liquids by adsorption produces secondary waste which has to be treated afterwards. The treatment can be e.g. high temperatures or a landfill. Photocatalysts such as CN6 can remove the dye under light irradiation but most times they have to be separated afterwards. Immobilisation of these photocatalysts can be one way to address this problem. The resulting photocatalyst layers were analysed in operando by near-ambient pressure XPS. This enabled us to detect the active species, i.e. oxygen radicals, at the surface, responsible for the dye degradation.

Porous silicon (PSi) offers extremely attractive optical, electronic and biofunctional properties for the development of biosensors. In the present work, we have studied the step by step sandwich biofunctionalization cascade of a PSi platform by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and, in parallel, we have developed a three electrode PSi device sensitive to changes in surface conductance. Prior to the NAP-XPS characterization, the organosilanization with glycidyloxy-propyl-trimethoxy-silane, the bioconjugation, and the gold nanoparticle (AuNP) sensitization layer were monitored by spectroscopic ellipsometry. The NAP-XPS analysis revealed outstanding results: a) the NAP-XPS chamber allows detecting the pristine PSi with negligible adventitious carbon contamination, b) the single oxygen bonded carbon component of the Glycidyl group dominates the C1s core level after organosilanization, c) the good progress of the biofunctionalization/recognition is confirmed by the increase of the silica to silicon component ratio in the Si2p core level and, d) the N1s core level describes identical features from the presence of aminoacid sequences in the capture/detection steps. A FET sensing of a prostate specific antigen (PSA) marker was performed through conjugation with AuNPs. For a given concentration of PSA (and AuNPs) the conductance increased with the increase of the gate voltage. For a given gate voltage, the conductance was observed to increase for increasing concentration of PSA. This allowed proposing a calibration line for the biosensor, which is valid from a clinically relevant range of 0.1 ng/mL.

X-ray photoelectron spectroscopy (XPS) has become a routine analysis method to determine the chemical composition and bonding states of elements of sample surfaces in many industrial applications, like materials development, failure analysis, quality control and device certification. To obtain significant results the analyses of such samples require a fast analysis with reliable quantification and stable data for repeated experiments. In standard XPS experiments under ultrahigh vacuum (UHV) conditions the significance of the results can be affected by changing surface compositions under the analysis conditions, different degrees of degassing and thus changing degrees of differential charging in insulating samples. In this publication the positive influence of XPS analysis under elevated pressures, often named Near-Ambient Pressure XPS or “Environmental XPS” is shown for different samples. Furthermore the process of charge compensation in gas pressures of 1–2 mbar is introduced, followed by a discussion of the perspectives of this “Environmental Charge Compensation”. The paper discusses the efficiency and stability of Environmental Charge Compensations for typical insulating test samples, as well as for different bulk insulators. The additional capability of XPS in elevated pressures is demonstrated on a superabsorbent polymer typically used in diapers, showing the difference of the analysis results for its wet and dry state. The paper ends with the example of a commercial printed circuit board demonstrating the power of the method for routine analysis of complete devices.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., at greater than 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS survey, Ca (3p, 2p, 2s), O 1s, C 1s, and N 1s narrow, and valence band spectra from a clamshell, a material of biological origin that would be challenging to analyze by conventional XPS approaches. Like most shells of biological origin, clamshells are primarily composed of calcium carbonate.

Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can be used to probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show O 1s, C 1s, and Ca 2p narrow scans and a survey NAP-XPS spectrum from a human urolith, i.e., a kidney stone, which is a biomaterial that could not be analyzed at moderate pressures by conventional approaches.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than ca. 2500 Pa. With NAP-XPS, XPS can probe moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, we show NAP-XPS of sesame seeds, a food sample that could not be analyzed at moderate pressures by conventional approaches. Survey spectra from three separate seeds are shown. In addition to the expected C 1s and O 1s signals, seeds show calcium. The C 1s narrow scans from the three seeds are well fit by four components. The largest of these is attributed to carbon singly bonded to oxygen (C—O), which suggests carboydrates or cellulose in the material. A small N 1s peak is observed in all the survey spectra.

Nitrogen fixation in a simulated natural environment (i.e., near ambient pressure, room temperature, pure water and incident light) would provide a desirable approach to future nitrogen conversion. As N≡N triple bond has a thermodynamically high cleavage energy, nitrogen reduction under such mild conditions typically undergoes associative alternating or distal pathways rather than follows a dissociative mechanism. Here we report that surface plasmon can supply sufficient energy to activate N₂ through a dissociative mechanism in the presence of water and incident light, as evidenced by in-situ synchrotron radiation-based infrared spectroscopy and near ambient pressure X-ray photoelectron spectroscopy. Theoretical simulation indicates that the electric field enhanced by surface plasmon, together with plasmonic hot electrons and interfacial hybridization, may play a critical role in N≡N dissociation. Specifically, AuRu core-antenna nanostructures with broaden light adsorption cross section and active sites achieve an ammonia production rate of 101.4 μmol·g^-1·h^-1 without any sacrificial agent at room temperature and 2-atm pressure. This work highlights the significance of
surface plasmon to activation of inert molecules, serving as a promising platform for developing novel catalytic systems.

Near-ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) is a less traditional form of XPS that allows samples to be analyzed at relatively high pressures, i.e., greater than 2500 Pa. With NAP-XPS, XPS can be used to analyze moderately volatile liquids, biological samples, porous materials, and/or polymeric materials that outgas significantly. In this submission, the authors present the NAP-XPS survey, C 1s, O 1s, Ca 2p, and P 2p narrow scans from a human adult molar tooth, a biological material that would be challenging to analyze by conventional approaches. No pretreatment or cleaning of this dental specimen was performed prior to analysis. Three different regions (top, middle, and root) of the tooth were analyzed. The survey spectra, which differed considerably from each other, show the presence of carbon, oxygen, nitrogen, calcium, and phosphorous. Tin and sulfur are also present in small amounts on the top part of the tooth. C 1s narrow spectra are well fitted with four synthetic peaks.

In this submission, we show survey, O 1s, and C 1s near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) spectra from a hard Italian cheese, a material that could not be analyzed by conventional approaches without special sample preparation. The C 1s spectrum is fit under the assumption that the surface of the cheese is primarily fat (triglyceride), which is expected to be the lowest free energy component of the material. The O 1s envelope corresponding to the cheese was well fit to two components of equal area.

A solar light-active copper-metal organic framework (Cu-MOF) was constructed through a multiple-linker
strategy employing 1,2,4,5-benzenetetracarboxylic acid (H4btec) and 4,40^´ -bis(1-imidazolyl)biphenyl (bimb)
as ligands. A reaction mixture consisting of ligands and Cu-metal salts was heated to a critical point in a
hydrothermal reactor. The constructed MOF was studied for materials chemistry through successive
analytical techniques. The MOF exhibited a planar structure as seen from the topography obtained from
electron microscopy and substantiated further by crystallographic analyses. Spectroscopic analyses clearly
revealed its remarkable ability to harvest visible light. Photoluminesce demonstrated the effect of organic
conjugation over the transition of d–d electrons. Our study clarified the crucial part played by ligand to
metal charge transfer in charge-carrier generation. The adopted bi-linker approach enhanced the
photoactivity and prolonged the lifetime of the charge carriers. This was evident in a solar photocatalysis
experiment through complete removal of 2-chlorophenol in a short period of time. The robust structural
stability provided by the linkers was established through thermogravimetric analysis, whereas photostability
was established through successive photocatalytic experiments employing the recovered MOF.

Design and synthesis of multi-dimensional metal organic frameworks has attracted much attention not only due to their intriguing structures and unique properties, but also for their potential applications especially in catalysis. Recently, much effort has been devoted to develop new photocatalyst based on MOFs, motivated largely by a demand for solving pollution problems in view of their potential applications in the green degradation of organic pollutants. MOFs, known as coordination polymers are crystalline materials constructed from metal ions or clusters bridged by organic ligands to form one-, two-, or three-dimensional infinite networks. There are several methods have been applied for synthesis of MOFs particularly solvothermal, hydrothermal, microwave-assisted, electrochemical, mechanochemical and sonochemical synthesis. In this work, new Cadmium and Copper based Metal Organic Framework (MOF) was synthesized under hydrothermal and solvothermal conditions. Its structure was resolved by single crystal X-ray diffraction and further characterized by Powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectra (IR), Thermogravimetric (TGA), UV-Vis, Photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) analysis. The Cd-MOF and Cu-MOF were photocatalytically active for degradation of 2-chlorophenol (2-CP) under solar light irradiation where 69% and 100% of phenol removal was observed respectively. To improve photocatalytic activity of Cd-MOF, different metal ions such as Ag+, Fe3+ and Zn2+ were introduced into the framework through ion-exchange reaction. The UV-Vis results revealed that Fe-Cd-MOF showed an enhanced photoresponse in the visible region, whereas the photoresponse of Ag-Cd-MOF and Zn-Cd-MOF in the ultraviolet light region. Photocatalytic performances of synthesized materials were investigated fordegradation of 2-CP. Among them, Cd-MOF intercalated with Fe3+ exhibited excellent photocatalytic activity compared with Cd-MOF, degrading 92% of 2-CP in 5 hours. It can be attributed to the intercalation of Fe3+, which reduced energy gap of pure MOF, thus increases photocatalytic efficiency.

Bacteria are inherently in a hydrated state and therefore not compatible to ultra‐high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing. This has changed with the development of near‐ambient pressure (NAP)‐XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP‐XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre‐dried at 4 mbar, and at 1 mbar after overnight pumping at 10⁻⁴ mbar. The high‐resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze‐dried and fast‐frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface.

Hydrogen energy is considered to be a promising alternative for the sustainable and environmentally friendly solution of the global energy problem. One of the major obstacles of hydrogen energy applications is to maintain safe and efficient storage of hydrogen which can also be achieved chemically using suitable carrier materials. Formic acid (HCOOH, FA) can be utilized as a hydrogen carrier due to its low molecular weight (46 g/mol) and high hydrogen density (%4.4 weight). FA is a stable, non-flammable, and non-toxic biomass side-product rendering it a perfect candidate for an alternative hydrogen vector. Design of novel heterogeneous catalysts which can substitute the existing homogeneous catalytic systems may allow overcoming catalyst isolation and recovery costs and associated logistical problems hindering their applications in on-board operations.

FA can be catalytically decomposed via dehydrogenation and dehydration reactions. Selective dehydrogenation of FA is crucial because, the production of CO from dehydration mechanism can suppress the activity of the catalyst by blocking/poisoning the precious metal sites. Consequently, development of CO-resistant, selective, catalytically active, and reusable heterogeneous catalysts has a great significance. In the current work, a new material that can produce H₂(g) from FA under ambient conditions in the absence of additives with high CO-poisoning tolerance will be introduced, which is comprised of Pd-based trimetallic active centers functionalized with Ag and Cr in addition to amine-functionalized MnO_x promoters dispersed on a SiO₂ support surface.

In this article, we focus on the features of a modern XPS software package: the Specslab Prodigy system, which is used in most SPECS instruments. Software packages are an integral part of almost any analytical instrument these days, and purchasing decisions are often based as much on the software of an instrument as its hardware.

Here, we discuss some of the software innovations that are part of the EnviroESCA. These capabilities make this instrument and other SPECS instruments relatively easy to use and improve their data collection and workup capabilities. Two areas of focus
here will be the software’s ability to save and allow examination of every individual narrow scan, and its ability to interlace during data acquisition, i.e., alternate between taking different narrow scans and survey scans to avoid taking a block of any one type of scan.

Two systems of suspended nanoparticles have been studied with near-ambient pressure x-ray photoelectron spectroscopy: silver nanoparticles in water and strontium fluoride—calcium fluoride core-shell nanoparticles in ethylene glycol. The corresponding dry samples were measured under ultra high vacuum for comparison. The results obtained under near-ambient pressure were overall comparable to those obtained under ultra high vacuum, although measuring silver nanoparticles in water requires a high pass energy and a long acquisition time. A shift towards higher binding energies was found for the silver nanoparticles in aqueous suspension compared to the corresponding dry sample, which can be assigned to a change of surface potential at the water-nanoparticle interface. The shell-thickness of the core-shell nanoparticles was estimated based on simulated spectra from the National Institute of Standards and Technology database for simulation of electron spectra for surface analysis. With the instrumental set-up presented in this paper, nanoparticle suspensions in a suitable container can be directly inserted into the analysis chamber and measured without prior sample preparation.

X-ray photoelectron spectroscopy is the most widely used surface analytical technique, and with good reason. It can quantitatively determine the elemental composition of the outer 5 - 10 nm of a material, and it is sensitive to the oxidation state/chemical environment of the elements it detects. We have described the fundamental operating principles of XPS in previous VT&C articles and other publications. 1-9 XPS has become a fairly mature technique. It was once used almost exclusively by surface scientists. Now it is employed by researchers in many disciplines. XPS has been widely used to characterize semiconductors, ceramics, glass, catalysts, electrochemical devices, biosensors, materials for chromatography, etc.