X-ray Photoelectron Spectroscopy Methods Research Articles

Preparation of Nano-spherical Iron Phosphate by Hydrothermal Method and Its Application as the Precursor of Lithium Iron Phosphate

Abstract First, nano-spherical iron phosphate was prepared using the hydrothermal method. Then, the carbothermal reduction method was applied to synthesize the LiFePO4/C composite material capable of good carbon coating effect with the prepared nano-spherical iron phosphate as a precursor. By means of scanning electron microscope, transmission electron microscope, Zeta potentiometer, inductively coupled plasma spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy, electrochemical testing, and other methods, the material was characterized and tested for its morphology, particle size, composition, structure, and electrochemical performance. According to the test results, when the initial mass concentration of Fe3+ in the reaction solution is 2%, the amount of N and S impurity is merely 19 and 27 ppm, respectively. In the meantime, particle size is small, with a range of roughly 50–100 nm, and a spherical morphology is shown. The synthesized LiFePO4/C retains its nano-spherical morphology, which leads to a desirable carbon coating effect and an excellent electrochemical performance. The first charge–discharge specific capacity at 0.1 C rate reached 163.7 and 161.4 mAh/g, the charge–discharge efficiency was 98.6%, and the capacity retention rate at 50 charge–discharge cycles at 1 C rate reached 98.52%.

Comparison of Gas Sensing Properties of Reduced Graphene Oxide Obtained by Two Different Methods.

In this study, the sensitivity of reduced graphene oxide structures (rGO) to the action of selected gases (especially hydrogen, but also nitrogen dioxide and ammonia) was examined. Two sensing structures, based on rGO structures, obtained by different methods of oxidation (the modified Hummers, and the modified Tour’s method respectively), were investigated. We show here that the method used for the oxidation of rGO influences the sensitivity of the sensing structure during contact with various gaseous atmospheres. We performed our experiments in the atmosphere, containing hydrogen in a concentration range from 0 to 4% in nitrogen or synthetic air, both in dry and wet conditions. The temperature range was from 50 °C to 190 °C. Finally, we checked how the resistance of the samples changes when the other gases (NO2, NH3) appear in tested gas mixtures. The gas investigations were supplemented by the characterization of rGOs materials using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 sorption method.

Intermediate valence of CeNi2Al3 compound and its evidences: Theoretical and experimental approach

We present measurements of magnetic, transport and electronic properties obtained for polycrystalline CeNi2Al3 intermetallic compound. Magnetic susceptibility χ(T) was investigated in the range from 2 to 700 K, and its behavior is characteristic of a compound with unstable valence, varying between Ce3+ and Ce4+. In the temperature range down to 2 K there was no trace of magnetic order, no anomalies in the temperature dependence of the specific heat were found. The Sommerfeld coefficient extracted from the linear term of the heat capacity takes a value of γ = 21 mJ/(mol K2). The dependence of S(T) is linear up to about 25 K, which is symptomatic of a thermopower in the Fermi's liquid regime.The structure of satellites in the Ce(3d) electron spectrum obtained by the X-ray photoelectron spectroscopy (XPS) method indicates that the states of Ce(4f) are of mixed valence character. Analysis of Ce(3d) states based on Gunnarsson-Schönhammer theory shows that the energy of hybridization of Ce(4f) states with a conduction band is about 78 meV. For more detailed information about electronic states the fully relativistic band structure was calculated within the density functional theory (DFT) for the first time. Below Fermi's energy, the density of states is mainly formed by Ni(3d) states hybridized with Ce(4f) ones.

Synergistic effects of microstructures and active nitrogen content on the oxygen reduction reaction performance of nitrogen-doped carbon nanofibers via KOH activation heat treatment

A series of nitrogen-doped carbon nanofibers (N-CNFs) have been successfully synthesized via electrospinning N,N-dimethylformamide/polyacrylonitrile followed by KOH activation heat treatment. The electrocatalysts are thoroughly studied with X-ray diffraction, field emission scanning electron microscope, transmission electron microscopy, nitrogen adsorption–desorption isotherms, X-ray photoelectron spectroscopy, respectively, and electrochemical method. The time of KOH activation heat treatment is found to yield a considerable effect on crystallinity, microstructure, chemical surface states, the total content of nitrogen and the active nitrogen configurations in all samples. The resulting N-CNFs-3.0 h catalyst shows remarkable advantages for ORR performance, including porous microstructures, high specific surface area, abundant exposed active sites and high content of ORR-active pyridinic-N. With these favorable features, N-CNFs-3.0 h exhibits an overall distinguished ORR performance in alkaline media compared to commercial 20 wt% Pt/C catalyst, which has a high onset potential of 0.9 V (vs. RHE), half-wave potential of 0.83 V (vs. RHE) and electron transfer number (3.93). The superior ORR of N-CNFs-3.0 h mainly originates from the synergistic effect of porous microstructures and high ORR-active pyridinic-N content, which could be optimized by changing KOH activation time. This work presents a facile strategy to controllably design and fabricate highly active ORR metal-free carbon-based electrocatalysts.

Hydrophilic poly(phenylene sulfone) membranes for ultrafiltration

Poly(alkylene oxide) based tri- and multiblock oligomers with hydrophobic poly(phenylene sulfone) blocks were evaluated as dope solution additives used for preparation of improved poly(phenylene sulfone) (PPSU) flat sheet (FS) and single bore (SB) ultrafiltration membranes by non-solvent induced phase separation (NIPS). Identical polymer dope recipes were used in both of FS membrane preparation and SB fiber spinning processes. PPSU membranes modified with 9.2 wt % Pluronic® F127 based additive, M2 (7.5 kDa PPSU/ Pluronic® F127), or Lutensol® AT80 based additive, T2 (7.5 kDa PPSU/ Lutensol® AT80), displayed compared to pristine PPSU membranes elevated hydraulic permeance ranging from 485 to 674 kg m−2 bar-1h−1 (pristine PPSU: 310 – 464 kg m−2 bar-1h−1), higher molecular weight cut-off values from 37.0 to 53.5 kDa (pristine PPSU: 21.4 – 23.7 kDa), lower contact angles of 46.4° and 49.8° (pristine PPSU: 86.7°) and reduced fouling propensity with irreversible fouling values of 10 % (pristine PPSU: 15 %) for diluted potting soil extract as model substance. The combined analysis methods of X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance spectroscopy (1H NMR) indicated modest surface enrichment of the additives in the filtration layer. Consequently, PPSU ultrafiltration membranes modified with additives T2 and M2 provide interesting alternatives to poly(ether sulfone) (PESU) and poly(vinylidene fluoride) (PVDF) based membranes for surface water filtration combining both excellent filtration characteristics with a long lifetime due to its higher chemical resistance.

Chemical Surface Reactivity and Morphological Changes of Bismuth Triiodide (BiI3) under Different Environmental Conditions.

Layered metal halides like BiI3 are of current interest in connection with both 2D materials and photovoltaics. Here, we present a facile new method for the preparation of millimeter-sized BiI3 single crystals. We use these crystals to study the surface reactivity of their (001) cleavage planes toward various environmental conditions by measuring morphological changes using atomic force microscopy and analyzing the formed species by means of X-ray photoelectron spectroscopy and X-ray diffraction methods. We find that freshly cleaved samples show atomically flat surface regions extending over several micrometers and reveal steps corresponding to single BiI3 layers. However, we also find that the surface deteriorates in air on a time scale of hours. By studying samples cleaved and stored under different conditions, we identify water as the agent initiating the changes in surface morphology, while under inert gas and dry oxygen, the surface stays intact. On the basis of the analysis of deteriorated long-term-stored samples we identify BiOI as the main product of hydrolysis. We also observe a second long-term decomposition route for samples stored under dynamic vacuum, where formation of BiI whiskers occurs. Overall, our findings emphasize the challenges associated with the surface reactivity of BiI3 but also demonstrate that well-ordered BiI3 surfaces can be obtained, which indicates that preparation of extended, atomically smooth BiI3 monolayers by exfoliation from bulk crystals should be possible.

Surface properties of SnO2 nanolayers prepared by spin-coating and thermal oxidation

In this work, comparative studies of the surface morphology and surface chemistry of SnO2 nanolayers prepared by spin coating with subsequent thermal oxidation (SCTO) in the temperature range of 400–700 °C using scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) methods, are presented. The SEM images show that SCTO SnO2 nanolayers contain partly connected irregular structures strongly dependent on the final oxidation temperature, with interconnected single grains of longitudinal shape and size, resulting in a flatter surface morphology with respect to the commonly used three-dimensional (3D) SnO2 thin films. In turn, AFM studies additionally confirm that SCTO SnO2 nanolayers after post-oxidation annealing at higher temperatures contain isolated grains of average lateral dimensions in the range of 20–50 nm having a rather flat surface morphology of average surface roughness defined by the root mean square factor at the level of ∼2 nm. From the XPS experimental research it can be concluded that, for our SCTO SnO2 samples, a slight surface nonstoichiometry defined by the relative [O]/[Sn] concentration at the level of 1.8–1.9 is observed, also depending on the final post-oxidation temperature, being an evident contradiction to recently published literature using x-ray diffraction data. Moreover, XPS experiments show that there is also a permanent small amount of carbon contamination present at the surface of internal grains of our SCTO SnO2 nanolayers, creating an undesired potential barrier for interactions with gaseous species when they are used as the active materials for gas sensing devices.

Supercapacitor performances of MnO2 and MnO2/ reduced graphene oxide prepared with various electrodeposition time

MnO2 and MnO2/Reduced graphene oxide composite electrodes with different electrodeposition time after alcohol infiltration were prepared by a simple electrochemical deposition method without any binder under argon atmosphere. Scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and other analytical methods were used to analyze the morphology, microstructure and other properties of the composite material. Galvanostatic charge-discharge, Cyclic Voltammetry, Chronoamperometry and Electrochemical impedance spectroscopy were used to assess the electrochemical performance of the prepared electrodes. MnO2/RGO composite electrode deposited in a short time (50 s) has excellent electrochemical performance, the specific capacitance can maintain 175 F g−1 at a high current density of 20 A g−1, and the energy density can reach 41.27 Wh Kg−1 (1 A g−1). In addition, it has lower charge transfer resistance in 1 M Na2SO4 solution (0.22 Ω).

Oxidative destruction of phenol on Fe/SiO2 catalysts.

In the present study, the sol-gel technique helped to obtain Fe-containing samples with a base of amorphous silicon dioxide from rice husks RH-Fe and RH-Fe-300. These materials are characterized by IR spectroscopy, X-ray phase and X-ray spectral analysis. It was shown that the samples contain silicate structures Si-O-Si(Fe) and are in an amorphous state. Structure of the surface layers of RH-Fe-300 catalyst particles was established for the first time using X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectra (EDX) methods. It was shown that the surface layers of the synthesized particles are oxygen depleted due to oxygen vacancies and silanol groups, therefore defects can form in its structure. Photocatalytic activity of the samples in the phenol oxidation reaction under ultraviolet and solar irradiation in the presence of hydrogen peroxide was studied. It was shown that the degree of phenol decomposition in the presence of RH-Fe for 24 hours under solar irradiation was 92%, in the presence of RH-Fe - 17%. Under two-stage irradiation (ultraviolet and solar), the percentage of phenol decomposition using both catalysts after a day amounted to more than 80%. It was established that RH-Fe-300 catalyst increases oxidation of phenolic compounds in alkaline rice husk hydrolysates under solar irradiation in the presence of hydrogen peroxide.

Investigations of chemical and atomic composition of native oxide layers covering SI GaAs implanted with Xe ions

Semi-insulating (100) oriented GaAs was irradiated with 250 keV Xe+ ions with different fluences. The native oxide layers formed in the air after implantation are investigated in this study. The surface density of atoms in the native oxide layer, determined using Rutherford backscattering spectroscopy with nuclear reaction (RBS/NR), increases with ion fluence in the range between 2 × 1013 cm−2 and 8 × 1014 cm−2. Using X-ray photoelectron spectroscopy (XPS) method, the chemical composition was analyzed. It has been found that the native oxide layer on GaAs samples is a mixture of Ga2O3, As2O3, As2O5 and GaAs compounds and the compounds concentration changes depend on ion fluences.

(Invited) Vanadium Based Phosphate, Phosphite, Oxalate Cathode Materials for Lithium Batteries

Commercial lithium ion batteries (LIBs) use layer-type compounds, lithium cobalt oxide (LiCoO2) or LiFePO4 as the cathode (positive electrode) and graphite (C) as the anode (negative electrode) material, and a non-aqueous Li- ion conducting electrolyte. The liquid electrolyte in the form of a solution or immobilized in a gel-polymer. LIBs with an operating voltage of 3.6 V are extensively used in the present-day portable electronic devices like, cell phones and other low power operated devices. For high-power applications like, electric/hybrid electric vehicles and back-up power supplies and, the LIBs need to satisfy several criteria, namely, cost-reduction, improvement in the energy density, safety-in-operation at high current charge/discharge rates and improvement in the low-temperature-operation. To satisfy the above criteria, researches are being carried out worldwide to find alternative cathode materials.In my presentation, I will discuss our group studies on V-based Flouro phosphates cathode materials. Specifically, I will focus bare and Fe doped-LiVPO4F, αI-LiVOPO4 and V-based metal organic framework materials, MX[(VO)2N2(C2O4)], where M= K, Li, Na , N= HPO4, HPO3. and LiSiV2O6. Materials were prepared variety of chemical methods carbothermal/Graphenothermal reduction, hot plate and hydrothermal methods. Materials were characterized by Rietveld refinement X-ray diffraction, X-ray photoelectron spectroscopy, Raman, XPS, Microscopy (SEM &TEM) and BET surface area methods. Electro analytical studies like cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy techniques. Interestingly V-based cathodes showed around 4 V redox couple (except LiSiV2O6) which is higher than that of LiFePO4 (3.5V vs. Li) and observed reversible capacity is order 80-140 mAh/g. Discuss in detail long term cycling studies and rate capabilities and reaction mechanisms. Keywords: Materials synthesis; Batteries; Cathodes; Electrochemical Properties; Energy storage

Quaternary Cu2HgGeSe4 selenide: Its electronic and optical properties as elucidated from TB-mBJ band-structure calculations and XPS and XES measurements

We report on band-structure calculations, within a density functional theory (DFT), of total and projected densities of states as well as experimental investigation of the electronic structure of Cu2HgGeSe4 using X-ray photoelectron spectroscopy (XPS) method. The present DFT calculations bring an excellent correspondence of the total density of states curve to the experimental XPS spectrum of valence electrons employing in the calculations modified Becke-Johnson (mBJ) functional in the type of Tran and Blaha (TB-mBJ) for exchange–correlation (XC) potential and, in addition, the spin–orbit coupling (SOC) effect and Hubbard correction parameter U (TB-mBJ + SOC + U technique). The basic optical constants are calculated within the TB-mBJ + SOC + U technique and they reveal a big perspective of using the Cu2HgGeSe4 compound in optoelectronic appliances.

A Mechanistic Study of CO Oxidation on New Catalysts CeFe0.5Sb1.5O6 and PrFe0.5Sb1.5O6 Using the X-ray Photoelectron Spectroscopy Method

X-ray photoelectron spectroscopy has been applied to examine the surface electronic structure of layered oxides CeFe0.5Sb1.5O6 and PrFe0.5Sb1.5O6 with PbSb2O6 structure (sp. g. P‑31m). The analysis of the XP-spectra for both compounds revealed only Ce3+ and Pr3+oxidation state before and after catalytic tests. The observed variation of the Sb5+/Sb3+ and Fe3+/Fe2+ ratios after catalysis can point to that CO oxidation on these catalysts proceeds by virtue of redox transformations Sb3+ ↔ Sb5+ and Fe3+ ↔ Fe2+ with direct involvement of lattice oxygen and anionic vacancies.

What Is the Value of Water Contact Angle on Silicon?

Silicon is a widely applied material and the wetting of silicon surface is an important phenomenon. However, contradictions in the literature appear considering the value of the water contact angle (WCA). The purpose of this study is to present a holistic experimental and theoretical approach to the WCA determination. To do this, we checked the chemical composition of the silicon (1,0,0) surface by using the X-ray photoelectron spectroscopy (XPS) method, and next this surface was purified using different cleaning methods. As it was proved that airborne hydrocarbons change a solid wetting properties the WCA values were measured in hydrocarbons atmosphere. Next, molecular dynamics (MD) simulations were performed to determine the mechanism of wetting in this atmosphere and to propose the force field parameters for silica wetting simulation. It is concluded that the best method of surface cleaning is the solvent-reinforced de Gennes method, and the WCA value of silicon covered by SiO2 layer is equal to 20.7° (at room temperature). MD simulation results show that the mechanism of pure silicon wetting is similar to that reported for graphene, and the mechanism of silicon covered by SiO2 layer wetting is similar to this observed recently for a MOF.

Effect of γ-irradiation on ruthenium-morin nanocomposite for trace detection of Ce(IV), Ce(III) and Dy(III)

The article reports on the generation of Ru-morin nanocomposites using a simple methodology in presence and in absence of γ-irradiation. The nanocomposites were characterized using several techniques including, N2 adsorption-desorption, Brunauer−Emmett−Teller (BET) method, transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, powder X-ray diffractometric (XRD) technique, dynamic light scattering (DLS) and X-ray photoelectron spectroscopic (XPS) methods. The results revealed the production of comparatively smaller sized particles with smaller pores when prepared in presence of energetic γ-irradiation. The irradiated nanocomposite was found to be an eligible candidate for analytical sensing of Ce(IV), Ce(III) and Dy(III) out of a set of different lanthanoids. The lowest values of limit of detection (LOD) out of all the pH conditions for Ce(IV), Ce(III) and Dy(III) were 0.09 μM (at pH 12), 0.08 μM (at pH 12) and 5.37 μM (at pH 2) respectively using absorption spectroscopy. The LOD of Ce(IV) at pH 7 was found to be 0.35 μM by fluorescence spectroscopic method. It is established that the sensing is a pH dependent phenomenon which enables a selective and mutually exclusive sensing of these three lanthanoids individually. The study was also extended towards two environmental samples viz., tap water and ground water with significant recovery of Ce(IV), Ce(III) and Dy(III) from tap water and Ce(IV) and Dy(III) from ground water.

Experimental and Theoretical Study of Electronic Structure of Zinc Phthalocyanines ZnPc and ZnPcF16

The electronic structure of zinc phthalocyanines ZnPc and ZnPcF16 is studied by X-ray emission and X-ray photoelectron spectroscopy methods. Experimental and theoretical parameters of the energy spectrum are analyzed along with the partial composition of highest occupied molecular orbitals (HOMOs) of the molecules of these compounds. It is shown that the frontier high-energy region of ZnPc HOMOs consists of 2pπ atomic orbitals (AOs) of nitrogens from non-equivalent groups (Nα, Nβ) and 2pπ orbitals of peripheral carbons (Cβγδ) with the participation of 3d orbitals of zinc which belong to both π (3dyz, 3dz2) and σ (3dxy) types. It is established that fluorine atoms and the central zinc atom in ZnPcF16 interact with each other by forming delocalized π orbitals with the participation of carbon pπ orbitals belonging to α, β, γ, δ groups as well as nitrogen pπ orbitals of α and β groups. The HOMO of ZnPcF16 consists mainly of 2px and 2py AOs of nitrogen (Nα and Nβ) and carbon (Cβ and Cγδ) with a small contribution of the 3dxz, yz orbital of zinc.

Plasma-Chemical Deposition of Anti-Reflection and Protective Coating for Infrared Optics

The films of amorphous hydrogenated carbon doped with Si and O were deposited onto the sample of crystalline silicon by method of plasma-chemical deposition in the mix of polyphenyl methylsiloxane vapors and argon. Physico-mechanical and optical properties of films were examined for their use as anti-reflection and protective coatings in infrared optics devices. Film transparency in the wavelength range of 2.5–8 μm was measured by method of infrared spectroscopy with a Fourier transform. The structure and composition of films were studied by methods of Raman and X-ray photoelectron spectroscopy. Hardness and other mechanical properties of films were determined by nanoindentation. It was shown that the double-sided deposition of a-C:H:SiOx films onto Si plates allows increasing their integrated transmission in the wavelength region of 3– 5 μm from 50 to 87%. The films possess excellent mechanical characteristics, thermal stability in the temperature range from room temperature to 500°С, and resistance to aqueous solutions of salt.

Influence of Nitrogen on the Microstructure, Hardness, and Tribological Properties of Cr–Ni–B–C–N Films Deposited by DC Magnetron Sputtering

Using the direct current reaction magnetron sputtering technique, Cr–Ni–B–C–N films are deposited onto silicon substrates by sputtering Cr–Ni and B–C targets in an Ar/N2 gas mixture. The microstructure, chemical bonds, hardness, and tribological properties of the films are characterized using the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) methods, and microindentation and tribological tests. The experimental results show that the microstructure and properties of the films change upon incorporation of nitrogen into the film composition. The Cr–Ni–B–C–N films are mainly composed of the nanocrystalline CrN phase with some fractions of the Ni, Cr2O3, and B2O3 crystalline phases embedded in a mixed amorphous environment. Addition of nitrogen gives rise to an increase in the film hardness to a maximum value of about 17 GPa at FN2 = 40 cm3/min, and then the hardness sharply decrease with a further increase in the FN2 flow rate. The incorporation of nitrogen into the structure of films improves their tribological and adhesion properties.

Enhanced removal of tris(2-chloroethyl) phosphate using a resin-based nanocomposite hydrated iron oxide through a Fenton-like process: Capacity evaluation and pathways

The effective removal of organophosphorus compounds (OPs) effectively from water environment remains an important but challenging task. In this study, a resin-based nanocomposite of hydrated iron oxide (HD1) was used as Fenton-like catalyst for effectively catalyzing the decomposition of hydrogen peroxide to degrade tris(2-chloroethyl) phosphate (TCEP). The results showed that HD1 was successfully prepared, which had great versatility, catalytic performance and adsorption capacity. Besides, HD1/H2O2 was capable of degrading TCEP completely with less than 0.2 mg/L of inorganic phosphorus (IP) in the effluent at the initial TCEP of 38 mg/L, pH = 4, H2O2 dosage of 20 mM, and the Kobs could result in about 1.0530 min−1 under identical conditions. More attractively, inorganic ions (i.e., Clˉ, CO32ˉ, SO42ˉ, NO3ˉ, HCO3ˉ, Ca2+, and Mg2+) exhibited moderate effect on TCEP degradation. The negative effect of natural organic matters (NOM) (i.e., HA) on the degradation of TCEP was responsible for competition for the active oxygen species. Combined with electron paramagnetic resonance (EPR) spectra, X-ray photoelectron spectroscopy (XPS) and other analytical methods and radical quenching experiments, the possible removal process of TCEP was discussed, including two processes of oxidative degradation and immobilization of IP. Besides, hydroxyl radicals (•OH) was the key active species that contributed to TCEP degradation through hydroxylation-oxidation and C–O bond cracking, and specificity adsorption of HFO on IP was revealed. Furthermore, the results showed that HD1 had desirable acid and alkali resistance. In the continuous running fixed bed column experiment, HD1 showed a satisfactory performance in cycle operations. This work proposed a new enhanced process for removing TCEP in water environment by HD1/H2O2, and the multi-functional material, HD1 was promising in treatment of water containing organic phosphorus pollutants. This will be believed that this study will provide new ideas and new materials for the treatment of organic phosphorus-based organic pollutants, and lay the foundation for further deepening and expanding the application of adsorption resins in the field of water pollution control.

Rheotaxially Grown and Vacuum Oxidized SnOx Nanolayers for NO2 Sensing Characteristics at Ppb Level and Room Temperature.

This work presents, for the very first time, very promising nitrogen dioxide (NO2) sensing characteristics of SnOx nanolayers obtained by the innovative and unique rheotaxial growth and vacuum oxidation (RGVO) processing technique. The NO2 gas sensing experiments were performed using the novel surface photovoltage gas sensing device. The measured detection limit at room temperature (RT) is as low as 10 ppb NO2 in synthetic air, whereas the detection limit calculated on the basis of signal to noise ratio is around 6 ppb NO2. For the complementary study of surface chemistry of RGVO SnOx nanolayers, including nonstoichiometry, presence of carbon contamination and surface bondings, the X-ray photoelectron spectroscopy (XPS) method was applied. The SnOx RGVO samples reveal nonstoichiometry because the relative concentration [O]/[Sn] equals 0.94 for the as deposited sample and increases upon subsequent air exposure and NO2 sensing. Moreover, carbon contamination has been recognized after exposing the RGVO SnOx nanolayers to the air and during the NO2 detection.