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Nondestructive nanofabrication on monocrystalline silicon via site-controlled formation and removal of oxide mask
摘要： A nondestructively patterned silicon substrate serves as an ideal support for forming high-quality optical structures or devices. A new approach was proposed for fabricating site-controlled structures without destruction on a monocrystalline silicon surface via local anodic oxidation (LAO) and two-step postetching. The nondestruction was demonstrated by conductivity detection with conductive atomic force microscopy (AFM), and an almost perfect crystal lattice was observed from the fabricated hillock by high-resolution transmission electron microscopy (HRTEM). By programming AFM tip traces for LAO processing, site-controlled nondestructive patterns with di?erent layouts can be produced. This approach provides a new route for realizing nondestructive optical substrates.
关键词： conductive atomic force microscopy,high-resolution transmission electron microscopy,local anodic oxidation,nondestructive nanofabrication,monocrystalline silicon
更新于2025-11-14 17:04:02
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The Preparation and Characterization of Fluorinated Graphene Oxide with Different Degrees of Oxidation
摘要： For many excellent graphene derivatives, tailoring the material properties is crucial to get a broader application. In the present work, a series of fluorinated graphene oxide (FGO) with various oxidation degree were synthesized using a modified Hummers method at different reaction temperatures. The structure and property of FGO were analyzed by X-ray diffraction (XRD), Fourier transform infra-red spectra (FT-IR), X-ray photoelectron spectra (XPS) and Zeta potential analysis. The results indicate that the oxygen contents range from 5.61 % to 21.96 % in FGO can be tuned by altering the reaction temperatures. The oxygen in FGO is presented mainly in the form of epoxide and carboxyl groups. With increasing reaction temperature from 50 °C to 90 °C, the oxygen content in FGO decreases and thicker multilayered FGO is formed with lower dispersibility.
关键词： Controllable oxidation,Fluorinated Graphene Oxide,Low temperature reaction
更新于2025-11-14 17:04:02
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Mechanical analysis of the interface bonding state of a TiO2 film/Si substrate
摘要： TiO2 film is prepared on the surface of a natural oxide layer of a monocrystalline silicon substrate via RF magnetron sputtering. HRTEM (High Resolution Transmission Electron Microscope) imaging and EDX spectroscopy are performed on the sample interface, demonstrating that the film sample has a two-layer structure. Combined with XRD, the analysis shows that the upper film is a crystalline TiO2 film with a thickness of approximately 30 nm and that the lower film is a natural amorphous SiO2 oxide film with a thickness of approximately 22 nm. A geometric phase analysis (GPA) and Hooke's law are used to analyse the stress and bonding state at the interfaces between the monocrystalline silicon substrate and the natural oxide layer, between rutile TiO2 and the natural oxide layer, and between anatase TiO2 and the natural oxide layer. It is concluded that the interface bonding state of the monocrystalline silicon/natural oxide layer is good and that the interface bonding state at the interface between rutile and the natural oxide layer is better than that between anatase and the natural oxide layer.
关键词： geometric phase analysis,Hooke's law,natural oxidation,interface bonding states,TiO2
更新于2025-11-14 17:04:02
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MOF-templated core-shell Co(II/III)@ZnO hexagonal prisms for selective oxidation of vanillyl alcohol
摘要： This work provides a facile strategy to prepare core-shell structured catalysts with MOF-templated metal active species embedded carbon matrix core and a functional metal oxide shell in a controllable way. The procedure features with the facile introduction of functional shell metal oxide and delivery of MOF morphology. Co(II/Ⅲ)@ZnO hexagonal prisms are fabricated with this procedure and ZIF-67 as the template. When being used in the selective oxidation of vanillyl alcohol to produce vanillin, ZnO shell plays an important role by faciliating redox of Co3+/Co2+ for promoting vanillyl alcohol oxidation to vanillin and protecting the Co species against leaching into the reaction system. Co(II/Ⅲ)@ZnO exhibits a conversion of 20% with a selectivity of 80% after a 2 h reaction and shows stability after 3 catalytic cycles.
关键词： selective oxidation,vanillin,MOF-templated,ZnO,core-shell
更新于2025-11-14 17:03:37
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Visible light-induced oxidation of aqueous arsenite using facile Ag2O/TiO2 composites: Performance and mechanism
摘要： Conversion of aqueous arsenite [As(III)] to less toxic arsenate [As(V)] is a critical step for the arsenic pollution remediation. In this study, Ag2O/TiO2 composites synthesized via the pH-induced precipitation method were employed into the photocatalytic oxidation of As(III) under visible light irradiation. X-ray diffraction, transmission electron microscope and X-ray photoelectron spectroscopy analysis verified the formation of Ag2O/TiO2 heterostructures. Compared to pure Ag2O and TiO2, the 30% Ag2O/TiO2 composite exhibited much higher photochemical reactivities for the oxidation of As(III) under visible light irradiation. Under the optimal conditions [pH=4.0, the photocatalyst dosage being 0.3 g L-1 and initial As(III) concentration being 10 mg L-1], the oxidation and removal percent of As(III) was 60.7% and 83.0% after reaction for 120 min, respectively. Moreover, the formation of Ag(0) over the surface of Ag2O by photo-induced electrons contributed to the high stability of Ag2O/TiO2 composite. It was also found that photo-generated holes and superoxide radicals played the predominant roles in the As(III) oxidation. The improved photocatalytic activities were attributed to the formation of the hetero-junctions between Ag2O and TiO2, the strong visible light absorption, and the high separation efficiency of photo-generated electron-hole pairs resulted from the Schottky barriers at the Ag-Ag2O interface.
关键词： visible light,arsenite oxidation,Ag2O/TiO2 composite,photocatalytic
更新于2025-11-14 17:03:37
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Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation
摘要： As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported due to their high OER activities during the past few decades. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during OER for these electrocatalysts, has not been understood yet, which urgently needs a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of electrocatalysts with a morphology change via Co(OH)2 intermediate during OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR) and other ex situ technologies. Moreover, based on this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in OER measurement can provide insights into the fundamental understanding of the mechanism for OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.
关键词： structural evolution,XPS,in situ TEM,water oxidation,cobalt chalcogenide
更新于2025-11-14 15:27:09
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Ambient surface stability of thin film nanocrystalline Cu <sub/>3</sub> SbSe <sub/>4</sub> and structure-property relationships
摘要： Nanocrystalline materials have a high surface area, and hence may be significantly more reactive than their bulk counterparts under ambient conditions. This may affect device function in unexpected ways. Here, high quality crystalline Cu3SbSe4 nanocrystals are synthesized through a hot injection route, and thin films are deposited through a ligand exchange procedure. The electronic conductivity of the films increases significantly upon exposure to air, up to 80 Ω-1cm-1. This increase in conductivity is correlated to a surface oxidation as observed by XPS. The observed changes in the film upon exposure to ambient conditions are suggested to be critical for understanding the properties of these materials as they are incorporated into devices.
关键词： surface oxidation,earth abundant,copper antimony chalcogenides,hot injection,Thermoelectrics,nanoparticles
更新于2025-11-14 15:19:41
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A dual TiO2/Ti-stainless steel anode for the degradation of orange G in a coupling photoelectrochemical and photo-electro-Fenton system
摘要： A dual-anode consists of stainless steel and TiO2/Ti electrodes is used to study the kinetics of the degradation of hazardous chemicals exemplified by azo dye orange G (OG) using a coupling photoelectrochemical catalytic and photoelectro-Fenton (PEC/PEF) system. Concurrent generation of hydroxyl radicals on the TiO2/Ti photocatalyst and in-situ generation of Fenton reagents on the stainless steel electrode greatly enhances the performance of the PEC/PEF electrodes over that of the PEC and the PEF alone process. The efficiency of the PEC/PEF process is a function of Fe2+ and H2O2 concentration OH? in the solution bulk, which promotes the oxidative degradation of OG and its byproducts. The mean carbon oxidation state (COS) is estimated to reflect the degree of mineralization. Based on the pseudo first-order kinetics with respect to OH?, OG, Fe2+, the corresponding reaction rates is established. UV–Vis spectrometry reveals the presence of four major intermediates, which helps establish the OG degradation pathways.
关键词： Photoelectrochemical catalytic oxidation,Orange G,Electro-Fenton,Photoelectro-Fenton,Electrochemical oxidation
更新于2025-09-23 15:23:52
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ZnO Micro- and Nanostructures Obtained by Thermal Oxidation: Microstructure, Morphogenesis, Optical, and Photoluminescence Properties
摘要： ZnO micro- and nanostructures were obtained through thermal oxidation of Zn powders at high temperature under air atmosphere. A detailed study of the microstructure, morphology, optical, and photoluminescence properties of the generated products at different stages of thermal oxidation is presented. It was found that the exposure time has a strong influence on the resulting morphology. The morphogenesis of the different ZnO structures is discussed, and experimental parameters for fabricating ZnO tetrapods, hollow, core-shell, elongated, or rounded structures by thermal oxidation method are proposed on the basis on the obtained results. Notoriously, the crystal lattice of the ZnO structures has negligible residual strain, although, the density of point defects increases when the thermal treatment is extended; as consequence, their visible luminescence upon UV excitation enhances.
关键词： growth mechanism,ZnO structures,thermal oxidation,physical properties
更新于2025-09-23 15:23:52
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Influence of thermal oxidation temperature on the microstructure and photoelectrochemical properties of ZnO nanostructures fabricated on the zinc scraps
摘要： In this paper, zinc oxide (ZnO) nanowires were synthesized by thermal oxidation method of zinc scrap at various temperatures ranging between 400 °C and 900 °C under air atmosphere. The influence of different temperature on the phase structures, surface morphologies and photoelectrochemical (PEC) properties of ZnO nanowires were investigated. The characterizations were carried out via X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The results showed that annealing temperature played a significant role on surface morphology and phase structure. The band gap energy of the ZnO nanowires changed between 3.12 and 3.194 eV. The photoelectrochemical (PEC) study of the ZnO nanowires was investigated in 0.1 M Na2SO4 aqueous solution. The PEC findings represented that the ZnO nanowire annealed at 600 °C had 252.2 mA/cm2 net photocurrent density which was the best efficiency and at least 10 times higher than that of the lowest one at 1.25 V (vs. VRHE). Mott-Schottky analysis showed that the ZnO nanowires behaved as n-type semiconductor. ZnO nanowire annealed at 600 °C had the highest carrier density value (Nd = 9.03 × 10^23). Moreover, the charge transfer behavior of the ZnO nanowires was determined by means of electrochemical impedance spectroscopy (EIS) measurements. As a result, this work recommends that the ZnO nanowires could be good candidate on PEC applications. Also, thermal oxidation method is an efficient method for fabrication of ZnO nanowires.
关键词： Thermal oxidation,Zn scrap,Electrochemical impedance spectroscopy (EIS),ZnO nanowires,Photoelectrochemical (PEC)
更新于2025-09-23 15:23:52