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Boosting Visible-light-driven Photooxidation of BiOCl by Promoted Charge Separation via Vacancy Engineering
摘要： The separation of electron-hole pairs has an important influence on the photocatalytic process on semiconductors. In this work, BiOCl nanosheets with oxygen vacancies (BiOCl-OVs) have been prepared by reconstructing small hydrophobic BiOCl nanosheets. The transient photoresponse and the electron spin resonance (ESR) results prove that the separation of the charge carriers can be promoted by the oxygen vacancies via trapping the photoexcited electrons. Due to the improved charge separation and wide absorption of the solar spectrum, more photogenerated charge carriers are produced, as confirmed by the photocurrent response and the ESR measurements of the reactive oxygen species ?O2- and ?OH. Consequently, BiOCl-OVs present enhanced photocatalytic properties towards NO removal. Our study illustrates the importance of the construction of vacancies for improving photocatalytic performance.
关键词： oxygen vacancies,charge separation,BiOCl,NO removal,photocatalytic
更新于2025-09-23 15:23:52
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Oxidized Metal Schottky Contacts on (010) β-Ga2 O 3
摘要： Oxidized Ir, Pd, Pt, Ag, and Au Schottky contacts (SCs) were fabricated on (010) β-Ga2O3 single crystal substrates via reactive rf sputtering using an O2:Ar plasma. The use of in-situ oxidizing conditions resulted in SCs with very high rectifying barriers in excess of 2.0 eV for all the metals investigated, representing an increase of 0.4 to 0.9 eV compared to the corresponding plain metal versions. Both the plain and oxidized metal SCs showed evidence of Fermi Level pinning with their laterally homogeneous barrier heights lying in narrow ranges of ~1.3 to 1.5 eV and ~2.2 to 2.4 eV, respectively, with little correlation with metal work function. This was attributed to the influence of metal-induced oxygen vacancies and gap states at the SC interface, respectively. The very high barriers of the oxidized SCs resulted in excellent high temperature performance with ~10 orders of magnitude of rectification at 180 oC, indicating the potential of this technique for the fabrication of high temperature unipolar devices.
关键词： Metal Induced Gap States,Fermi Level Pinning,Oxygen Vacancies,Semiconductor Interfaces,Schottky Diodes
更新于2025-09-23 15:22:29
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Ultrafast methanol sensing properties of nano-spindle like In2O3 hierarchical structures with oxygen vacancies
摘要： Unique nano-spindle like In2O3 hierarchical structures have been successfully prepared using a simplified solvothermal method. The micromorphology and crystalline structure of the as-obtained are characterized by SEM, TEM, and XRD. Morphology analysis reveals that the nano-spindle like In2O3 hierarchical structures are composed of numerous ordered nanorods. The optical properties of the samples are also studied, and it is confirmed that the presence of a large amount of oxygen vacancies in the as-synthesized samples. The as-synthesized nano-spindle like In2O3 hierarchical structures are used for the detection of the methanol gas. The sensing properties of the as-manufactured sensor are carefully discussed and the sensor shows outstanding methanol sensing performance, especially ultrafast response time (<1 s). The sensing mechanism is also discussed. This work offers the possibility to manufacture low-cost, high-performance methanol sensor based on the as-synthesized nano-spindle like In2O3 hierarchical structures.
关键词： Oxygen vacancies,Methanol sensing performance,Hierarchical structures,Nano-spindle like In2O3
更新于2025-09-23 15:22:29
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Room-temperature ferromagnetism and morphology evolution of SnO2 flower-like microparticles by Zn-doping
摘要： We report on the growth of undoped and Zn-doped flower-like microparticles, which are constituted of SnO2 acicular nanoparticles (NPs) aggregated by one of their ends. NPs were synthesized by the hydrothermal method. The morphology of the NPs progressively changes from truncated rods to sharp needles by the effect of Zn doping. This morphology evolution is attributed to an increase of the surface free energy of the NPs' facets and to a modification of the growth front direction. Undoped samples exhibit a very low magnetization attributed to single positive charged oxygen vacancies, while Zn-doped samples exhibit ferromagnetic ordering due to Zn atoms in Sn substitutional positions (ZnSn). Thermal treatment under reducing atmosphere leads to the creation of an excess of VO conducting to a reduction of the magnetization, demonstrating that ferromagnetism in Zn-doped SnO2 NPs is attributed to ZnSn defects and to the octahedrally coordinated oxygen atoms.
关键词： Magnetization,Oxygen vacancies,SnO2 nanoparticles,Morphology,Zn-doped
更新于2025-09-23 15:22:29
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Synthesis of oxygen deficient bismuth oxide photocatalyst for improved photoelectrochemical applications
摘要： The present paper reports the effect of nitrogen modification on photoelectrochemical (PEC) water oxidation behavior of Bi2O3 semiconductor thin film. The semiconductor particles were synthesized via hydrothermal route using Bi(NO3)3 as a Bi3+ ion precursor and urea as the nitrogen source followed by drop-cast the particles and annealing the film at 600oC. The synthesized Bi2O3 exhibited band gap energy of 3.01 eV, calculated from the UV-vis absorption spectrum which decreases to 2.75eV through N-modification. Water oxidation behavior of the material has been tested through linear sweep voltammetry under periodic illumination. Highest photo-current of 180 μAcm-2 has been measured for water oxidation reaction at 0.95V vs. Ag/AgCl, under illumination of 35mWcm-2. N-incorporation can enhance the photocurrent up to 50% whereas the visible responsiveness of the material improves significantly as confirmed from electrochemical action spectra and UV-visible absorption spectra. The photocatalytic activity of the semiconductor particles was confirmed through decoloration of Rhodamine-B dye, by spectrophotometric measurements.
关键词： Hydrothermal synthesis,Oxygen vacancies,Bismuth oxide photocatalyst,PEC water oxidation.,N-modification
更新于2025-09-23 15:22:29
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The effects of thermal annealing on the structural and electrical properties of Zinc Tin oxide thin films for transparent conducting electrode applications
摘要： The as-deposited and annealed Zinc tin oxide (Zn2SnO4) thin films were deposited by electron beam evaporation technique and were characterized for the structural, optical and electrical properties. The x-ray diffraction technique revealed the amorphous nature of as-deposited thin film while the films annealed at 400, 500 and 6000C in air were found to be polycrystalline. The phase change from amorphous to crystalline Zn2SnO4 results in the higher resistance as revealed by resistance versus temperature measurements. From the Hall Effect, the as deposited film shows the electron mobility and carrier concentrations (electron) equal to 33cm2/V.s and 8.361x 1017cm-3 respectively. The agglomeration of grains in annealed thin films are observed by Atomic Force Microscopy (AFM) technique.The peaks in Optical transmission spectra, observed by using the UV-Vis spectroscopy confirm the creation of sub levels between conduction band minimum and valence band maximum after annealing. The band gaps calculated by Tauc plot explore the possibility of shifting the Fermi level towards valence band maximum after thermal annealing.
关键词： Annealing temperature,Zn2SnO4,Band gap,Oxygen vacancies,Electron beam evaporation,TCOs
更新于2025-09-23 15:22:29
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Three-in-one oxygen vacancy: whole visible-spectrum absorption, efficient charge separation and surface site activation for robust CO2 photoreduction
摘要： Exploitation of efficient catalysts to realize solar-driven conversion of inert CO2 into useful fuels confronts big challenges owing to the poor photoabsorption, sluggish charge separation and inefficient surface reactive sites of photocatalysts. Herein, we report a facile and controllable in situ reduction strategy to create surface oxygen vacancies (OVs) on Aurivillius-phase Sr2Bi2Nb2TiO12 nanosheets. Sr2Bi2Nb2TiO12 nanosheets are for the first time prepared by a mineralizer-assisted soft-chemical method, and the introduction of OVs on the surface of Sr2Bi2Nb2TiO12 not only extends photo-response region, but also tremendously promotes separation of photo-induced charge carriers. Moreover, the adsorption and activation of CO2 molecules on the surface of the catalyst are largely enhanced. In the gas-solid reaction system without any co-catalysts or sacrificial agents, OVs-abundant Sr2Bi2Nb2TiO12 nanosheets show an outstanding CO2 photoreduction activity in producing CO with a rate of 17.11 μmol g?1 h?1, ~58 times higher than that of the bulk counterpart, surpassing most previously reported state-of-the-art photocatalysts. Our study provides a three-in-one integrated solution to advance the comprehensive performance of photocatalysts for solar-energy conversion and generation of renewable energy.
关键词： Sr2Bi2Nb2TiO12 nanosheets,oxygen vacancies,charge separation,photocatalytic CO2 reduction
更新于2025-09-23 15:22:29
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Atomic-thick TiO <sub/>2</sub> (B) nanosheets decorated with ultrafine Co <sub/>3</sub> O <sub/>4</sub> nanocrystals as a highly efficient catalyst for lithium-oxygen battery
摘要： Development of high efficient catalysts based on transition metal oxides (TMOs) is desirable, and remains a big challenge for lithium-oxygen (Li-O2) batteries. In the present work, atomic-thick TiO2(B) nanosheets decorated with ultrafine Co3O4 nanocrystals (Co3O4-TiO2(B)) was synthesized and utilized as cathode catalyst in Li-O2 batteries by designing a hybrid and inducing oxygen vacancies. The XPS characterization results suggested that the introduction of Co3O4 nanocrystals could induce numerous oxygen vacancies in the TiO2(B) nanosheets through Co doping in the hybrid catalyst. The subsequent electrochemical experiments indicated that the Li-O2 batteries with the prepared hybrid catalysts showed high specific capacity (11000 mAhg-1), and good cycling stability (200 cycles at a limited capacity of 1000mAhg-1) with low polarization (above 2.7V for discharge medium voltage and below 4.0V for charge medium voltage within 80 cycles). Furthermore, a possible working mechanism was proposed for a better understanding of the high performance of Co3O4-TiO2(B) catalysts for the Li-O2 batteries. This work also provided some new insights into designing efficient catalysts through interface engineering between 2D (two dimentional) TMOs and 0D (zero dimentional) TMOs for Li-O2 batteries or other catalysis related fields.
关键词： film-like Li2O2,oxygen vacancies,TiO2(B) nanosheets,Co3O4 nanocrystals,Li-O2 battery
更新于2025-09-23 15:21:21
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Enhanced Charge Transport and Increased Active Sites on α-Fe <sub/>2</sub> O <sub/>3</sub> (110) Nanorod Surface Containing Oxygen Vacancies for Improved Solar Water Oxidation Performance
摘要： The e?ect of oxygen vacancies (VO) on α-Fe2O3 (110) facet on the performance of photoelectrochemical (PEC) water splitting is researched by both experiments and density functional theory (DFT) calculations. The experimental results manifest that the enhancement in photocurrent density by the presence of VO is related with increased charge separation and charge-transfer e?ciencies. The electrochemical analysis reveals that the sample with VO demonstrates an enhanced carrier density and reduced charge-transfer resistance. The results of DFT calculation indicate that the better charge separation is also contributed by the decrease of potential on the VO surface, which improves the hole transport from the bulk to the surface. The reduced charge-transfer resistance is owing to the greatly increased number of active sites. The current study provides important insight into the roles of VO on α-Fe2O3 photoanode, especially on its surface catalysis. The generated lesson is also helpful for the improvement of other PEC photoanode materials.
关键词： oxygen vacancies,α-Fe2O3,photoelectrochemical water splitting,charge-transfer efficiencies,density functional theory,charge separation
更新于2025-09-23 15:21:21
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Oxygen-Defected Molybdenum Oxides Hierarchical Nanostructure Constructed by Atomic-Level Thickness Nanosheets as an Efficient Absorber for Solar Steam Generation
摘要： Solar steam generation is a potential approach for fresh water recycling, thus attracting increasing attention recently. To further promote water evaporation rate, some new materials need to be developed, such as plasmonic transition metal oxides. In this work, we report an oxygen-defected molybdenum oxides hierarchical nanostructure (MoOx HNS) composed of ultrathin nanosheets with atomic-level thickness, which is demonstrated as an efficient absorber for solar steam generation. Benefiting from broadband light absorption and special assembled architecture, the resulting MoOx HNS loaded on a PTFE membrane (MoOx HNS Membrane) exhibits excellent performance for boosting steam generation rate. Under 1 sun (1 kW m?2) illumination, the evaporation rate can reach at 1.255 kg m?2 h?1, with the energy conversion efficiency of 85.6%, which is one of the best performance compared with other desalination materials. Meanwhile, the MoOx HNS Membrane can achieve high-performance seawater desalination in both laboratorial and outdoor conditions. The enhanced water evaporation performance can be attributed to the synergistic effects of the efficient solar-to-thermal conversion and the unique channel structure. This work expands the scope of investigated materials which can be applied in seawater desalination system.
关键词： MoOx hierarchical nanostructure,seawater desalination,photothermal conversion,oxygen vacancies,solar steam generation
更新于2025-09-23 15:21:21