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Enhanced degradation of BPA in water by PANI supported Ag/TiO2 nanocomposite under UV and visible light
摘要： PANI supported Ag@TiO2 nanocomposite was synthesized via oxidative polymerization of aniline on Ag@TiO2. The Ag@TiO2 nanocomposite was synthesized by the photo reduction of Ag nanoparticles on hydrothermally synthesized TiO2 nanofibers. Raman analysis revealed that the anatase phase of TiO2 was synthesized showing typical peaks at 195 cm-1, 396 cm-1, 514 cm-1, and 637 cm-1. The incorporation of PANI, a carbonaceous material was confirmed by appearance of D-band and G-band in Ag@TiO2-PANI that were located at 1505 cm-1 and 1603 cm-1 respectively. X-ray diffraction (XRD) analysis confirmed the anatase phase of TiO2 was synthesized. Transmission electron microscopy analysis (TEM) analysis revealed that TiO2 nanofibers were synthesized successfully and Ag nanoparticles of different sizes were deposited on their surface. X-ray Photon Spectroscopy (XPS) survey scan of the Ag@TiO2-PANI-nanocomposite revealed that the nanocomposite was made from C, O, Ag, Ti, and N. DRS and Tauc`s plot estimated the band gap of Ag@TiO2-PANI to be 3.0 eV. A comparative study of the photocatalytic performance of Ag@TiO2-PANI catalyst showed better degradation performance under both conditions than pristine TiO2, and Ag@TiO2 with a degradation of up to 99.7% under visible light irradiation. The degradation experiments showed that the reactive species that were dominant in the degradation of BPA were h+ and .O2-. The nanocomposite was re-used to degrade BPA for up to four cycles without losing much of its photocatalytic ability with a removal of at least 90% in the fourth cycle.
关键词： Bisphenol A,Ag@TiO2-PANI,visible light,X-ray photoelectron spectroscopy,UV
更新于2025-09-23 15:22:29
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ZnO-based nanocomposites prepared by a vapor phase route, investigated by XPS
摘要： Nanostructured materials based on ZnO, eventually functionalized with titanium oxide (TiO2) or tungsten oxide (WO3), were fabricated on fluorine-doped tin oxide-coated glass substrates by a combined chemical vapor deposition/radio frequency-sputtering route. In particular, the present work focuses on the use of x-ray photoelectron and x-ray excited Auger electron spectroscopies for a detailed investigation of the system O 1s, Zn 2p3/2, Zn 3p, and Zn LMM core levels, as well as Ti 2p and W 4f photoelectron peaks. In a nutshell, the results of these analyses highlight the obtainment of pure ZnO nanodeposits, as well as of ZnO-TiO2 and ZnO-WO3 composites, in which the identity of each component is preserved, and the occurrence of an electronic interplay between ZnO and WO3 phases in the latter system.
关键词： RF-sputtering,CVD,x-ray photoelectron spectroscopy,WO3,TiO2,ZnO
更新于2025-09-23 15:22:29
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Optimized chemical cleaning procedure for enhancing photoemission from GaAs photocathode
摘要： To obtain cleaner GaAs photocathode surface, various wet chemical cleaning methods to remove the oxides and carbon contaminations from the surface of GaAs photocathode are investigated, and an improved chemical etching method is presented to further enhance the cathode photoemission performance. By means of X-ray photoelectron spectroscopy analysis, characteristics of these methods are summarized. HF solution can effectively reduce surface oxides, but it does not effectively act on the absorbed carbon contaminations. The mixed solution of HCl and isopropanol scores well in removing carbon contaminations, but the ability of removing oxides is relatively weaker. The mixed solution of HCl and deionized water right after the mixed solution of H2SO4, H2O2 and deionized water is unfavorable to reduce Ga oxides. The improved chemical etching method, which uses HF solution followed by the mixture of HCl and isopropanol has more advantages in removing oxides and carbon contaminations at the same time. Moreover, a hydrophobic surface is obtained by using the improved method, which also plays a role in the contaminations removal. The quantum efficiencies of GaAs photocathode undergoing various wet chemical cleaning procedures are compared after subsequent heat treatment and activation. The results show that the chemical treatment of HF solution followed by the mixture of HCl and isopropanol can help GaAs photocathode obtain higher activated photocurrent and quantum efficiency.
关键词： Chemical cleaning,GaAs photocathode,Quantum efficiency,X-ray photoelectron spectroscopy
更新于2025-09-23 15:22:29
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Layer by layer deposition of alternate carbon nanotubes and Ni films for efficient multilayer thin film temperature gauges
摘要： This study reports a novel approach for growing multilayer thin films consisting of alternate layers of carbon nanotubes (CNT) and nickel on Si (1 0 0) substrates and justifies their use in thin film temperature sensors. A low pressure chemical vapor deposition system was employed for synthesizing CNT films, while Ni films were deposited by electrodeposition. Porous-Si was used as substrate to increase adhesion between the layers of the multilayer structure. The structure of the multilayer films and the quality of the CNT grown were analyzed using several characterization methods, including scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray auger electron spectroscopy and Raman spectroscopy. The electrical characteristics were investigated using a van der Pauw setup and the effect of the increasing number of CNT layers in the multilayer structure was studied. The sensitivity of the multilayer film was found to increase with increasing number of CNT layers, despite the decrease of the temperature coefficient of resistance. On the other hand, the initial resistance was found to increase. Results indicated that these multilayer structures are appropriate for fabricating highly sensitive thin film gauges that can detect lower heat fluxes with more accuracy.
关键词： carbon nanotubes,thin film gauges,surface and interface chemistry,porous silicon,adhesion sensing,x-ray photoelectron spectroscopy
更新于2025-09-23 15:22:29
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Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO
摘要： Mesoporous NiO films were deposited by means of a screen printing technique onto fluorine-doped tin oxide transparent electrodes and consequently sensitized with Erythrosin B (EryB) dye. The obtained colored NiO material was used as a working electrode in a three-electrode cell to study the evolution of the triple semiconductor/dye/electrolyte interface upon electrochemical polarization in dark conditions. The electrolyte was a solution of I3?/I? in acetonitrile, with the redox couple representing the typical redox shuttle of dye-sensitized solar cells (DSCs). The adopted electrochemical conditions were devised in order to simulate the actual electrical environment of the NiO/dye photocathode in a light-soaked DSC. The use of a benchmark sensitizer EryB and of the most widely used redox mediator I3?/I? is particularly meaningful for the study of the adsorption dynamics and the determination of possible degradative phenomena on the basis of the behavior of numerous analogue systems. Therefore, for the first time, the evolution of the NiO/EryB/I3?/I? multiple interface was investigated combining the electrochemical characterization with ex situ spectroscopic analysis by means of X-ray photoelectron spectroscopy. The resulting picture shows that EryB in the immobilized state promotes the redox processes based on the I3?/I? couple. Moreover, the EryB sensitizer inhibits the phenomena of recombination between the metal oxide semiconductor and the redox couple.
关键词： X-ray photoelectron spectroscopy,Sensitized NiO,Dye-sensitized solar cells,Redox active species,Adsorption dynamics,Polarized surfaces
更新于2025-09-23 15:22:29
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CoGe surface oxidation studied using X-ray photoelectron spectroscopy
摘要： Cobalt germanides have been widely studied as semiconductor contact materials, but recent theoretical studies suggest that they may also be excellent catalysts for methane steam reforming with stabilities and activities comparable to more expensive noble metal catalysts. We have sputter deposited CoGe alloy films and characterized their structure and morphology after post-deposition annealing in high vacuum up to 1000 °C. We used X-ray photoelectron spectroscopy to study the initial oxidation of amorphous and crystalline CoGe alloy surfaces under low pressures of O2 and H2O. The oxidation rate in O2 was found to be faster for an amorphous CoGe surface compared to a crystalline surface. We also found that there was little difference in the oxidation rate in H2O for either amorphous or crystalline surfaces. During O2 oxidation, the crystalline surface preferentially forms GeO and the amorphous surface preferentially forms GeO2. We have also observed preferential oxidation of Ge in the CoGe thin films. During temperature programmed desorption studies, we found that GeO desorption begins near 350 °C and that GeO2 decomposes to GeO and desorbs near 700 °C. More studies of CoGe catalysts are warranted, however GeO desorption may be a concern under reaction conditions when the film is subjected to an oxidizing environment.
关键词： Oxidation,Cobalt germanium,Temperature programmed desorption,Atomic force microscopy,X-ray photoelectron spectroscopy,X-ray diffraction
更新于2025-09-23 15:21:21
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Composition analysis of Ta <sub/>3</sub> N <sub/>5</sub> /W <sub/>18</sub> O <sub/>49</sub> nanocomposite through XPS
摘要： A characterization of a nanocomposite material consisting of Ta3N5 nanoparticles and W18O49 nanowires is presented. The material is of interest for photocatalytic applications, with a focus on pollution reduction through the photodegradation of dye waste; under white light illumination, the combination of Ta3N5 and W18O49 yielded an enhanced rate of dye degradation relative to Ta3N5 particles alone. The facile method of synthesis is thought to be a promising route for both upscale and commercial utilization of the material. X-ray photoelectron spectroscopy revealed a core–shell composite structure with W18O49 present as an overlayer on Ta3N5; the analyzed spectra for the C 1s, O 1s, Ta 4f, N 1s, W 4f, and Na 1s regions are reported. It should be noted that due to differential charging of the underlying Ta3N5 component relative to the W18O49 shell, an additional uncompensated voltage shift may exist in the Ta 4f and N 1s spectra.
关键词： x-ray photoelectron spectroscopy,XPS,dye degradation,W18O49,nanowires,composite,Ta3N5,photocatalysis
更新于2025-09-23 15:21:21
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Valence band behaviour of zirconium oxide, Photoelectron and Auger spectroscopy study
摘要： In this study X-ray Photoelectron Spectroscopy and Ultraviolet Photoelectron Spectroscopy were combined to investigate the effect of oxygen incorporation on the valence band behaviour of ZrOx. The Auger transitions involving valence bands are found to mimic the self-folded density of state measured using Ultraviolet Photoelectron Spectroscopy. The valence band once constructed in a sub-oxide form, stays at a fixed energy position despite the change in the stoichiometry. This behaviour is found to be useful in setting a reference for X-ray Photoelectron Spectroscopy charge correction. The results of the charged corrected spectra were compared to other methods and found to be in great agreement. Finally, a correlation between the core-level binding energy and the structural property of ZrOx is given.
关键词： valence band,Ultraviolet Photoelectron Spectroscopy,X-ray Photoelectron Spectroscopy,Photoelectron,zirconium oxide,Auger spectroscopy
更新于2025-09-23 15:21:01
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Effect of Ga introduction during the second stage of a coevaporation process of Cu(In,Ga)Se2 layers at low temperature on polyimide substrates
摘要： A proper control of Ga concentration pro?le is mandatory to achieve high e?ciency Cu(In,Ga)Se2 (CIGS) solar cells. At low temperature, deep gradients, detrimental for carriers' di?usion, are obtained when CIGS is deposited with a standard three-stage process: an optimization of the process is needed. In this study, we show the impact of a modify three-stage process on the depth of the notch by introducing Ga ?ux during the second stage from 0 nm/min to 1.1 nm/min. A higher open circuit voltage compensated by a lower short current density is obtained due to higher band gap energy. The surface and the bulk of the CIGS layer was analyzed at the end of the second stage by coupling di?erent characterization techniques: glow discharge optical emission spectroscopy, Raman and X-ray photoelectrons spectroscopy. The presence of binary compounds as well as a Ga enrichment at the end of the second stage are observed when Ga is introduced during the second stage.
关键词： low temperature,X-ray photoelectron spectroscopy,solar cells,Cu(In,Ga)Se2,three-stage process,glow discharge optical emission spectroscopy,Raman spectroscopy,CIGS,Ga concentration pro?le
更新于2025-09-23 15:21:01
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The effect of Zn3N2 phase decomposition on the properties of highly-doped ZnO: Al, N films
摘要： Study of Al-N simultaneous doping and thermal annealing influence on the properties of ZnO films is very important for achievement as p-type conductivity in the films as for improvement the performance of ZnO-based ultraviolet detectors. Highly-doped ZnO:Al,N films containing the Zn3N2 phase (ZnO:Al,N-Zn3N2) were grown on Si substrates by magnetron sputtering using a layer-by-layer growth technique. Our work presents a comparative study of the structure, optical and electronic properties of highly-doped as-grown and annealed ZnO:Al,N films. It was shown that the thermal annealing of ZnO:Al,N-Zn3N2 film at atmospheric conditions allows to decompose the Zn3N2 phase. The features of this phenomena on the properties of ZnO:Al,N films were investigated and discussed in detail by using X-ray diffraction, energy dispersive X-ray analysis, Raman scattering, photoluminescence, X-ray photoelectron spectroscopy and X-ray emission spectroscopy.
关键词： Radio-frequency magnetron sputtering,Zinc oxide,Nitrogen-aluminum doping,Photoluminescence,X-ray photoelectron spectroscopy,Thin films,X-ray diffraction,Raman scattering
更新于2025-09-23 15:21:01