- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Significant enhancement of photoactivity in one-dimensional TiO2 nanorods modified by S-, N-, O-doped carbon nanosheets
摘要： Titanium dioxide (TiO2) represents one of the most active photocatalysts among metal oxides for the degradation of pollutants and for solar water splitting to produce hydrogen. The most critical drawbacks hindering its broad practical use are the absorption majorly in the UV part of solar spectrum and slow charge dynamics. Combination of TiO2 with a suitable partner in a hybrid nanostructure can effectively address these drawbacks. Here we report a novel nanocomposite system based on one-dimensional TiO2 nanorods wrapped with a sulfur-, nitrogen-, and oxygen-doped carbon (SNOC) nanosheets. The SNOC nanosheets are synthesized by a cost-effective and facile route using eco-friendly carrageenan as a sulfur, oxygen, and carbon source and urea as a nitrogen source. Silica was used as the templating agent that leads to large surface area materials after its removal at the end of the synthesis. Therefore, the synthesized material exhibits superior photocatalytic performance for decoloring representative Rhodamine B (RhB) under visible light irradiation. SNOC shows the apparent rate constant of 7.6 × 10–3 min–1, which is almost 3 times higher than that of a SNOC material without using silica (2.8 × 10–3 min–1). This performance of doped carbon material can be assigned to the effect of large surface area and effective visible light adsorption. The TiO2 NRs / SNOC nanocomposite was investigated for photoelectrochemical water splitting showing much higher photocurrent densities (0.85 mA cm–2) than pure TiO2 nanorod arrays (0.35 mA cm–2), which was due to significant improvement in the charge transfer dynamics and co-catalytic effect of SNOC. All the materials prepared were evaluated on the basis of physical properties such as crystalline structure, optical absorption, surface topography, and electronic properties.
关键词： Water splitting,Photoelectrochemistry,Photocatalysis,Heterojunction,TiO2 nanorods,S, N, O-doped mesoporous carbon
更新于2025-09-23 15:23:52
-
Porous WO3 monolith-based photoanodes for high-efficient photoelectrochemical water splitting
摘要： We report a successful fabrication of low-cost, high-efficient, structurally-rigid, porous WO3 photoelectrochemical (PEC) catalysts using polystyrene as the template by a sol-gel method and a high-temperature annealing treatment. The scanning electron microscopy and Brunauer-Emmett-Teller surface analysis results indicate that such WO3 monoliths possess a porous structure and a large specific surface area, which can supply lots of photogenerated charge transfer pathways as well as more surface PEC active sites. Compared with a commercially available WO3, our highly porous WO3 PEC catalysts show an excellent PEC water splitting activity. Particularly, the porous WO3 photoanodes calcinated in the presence of oxygen atmosphere at 450 °C for 7 h show the best PEC performance exhibiting the photocurrent density of 0.97 mA/cm2 at 1.23 V versus reversible the hydrogen electrode and the incident photon-to-current conversion efficiency up to 48.9% at 420 nm in 0.5 M Na2SO4 electrolyte under AM 1.5 G irradiation. Such excellent PEC performance is due to the high porosity of the WO3, promoting the fast transfer and the separation rate of photogenerated carriers during the PEC water splitting process.
关键词： Water splitting,Porous structures,Energy conversion,WO3,Photoanode
更新于2025-09-23 15:23:52
-
Stoichiometric and non-stoichiometric tungsten doping effect in bismuth vanadate based photoactive material for photoelectrochemical water splitting
摘要： In photoelectrochemical (PEC) water splitting, BiVO4 has attracted attention due to its favorable band gap but it suffers low PEC performance due to poor conductivity. The vast majority of publications on this system has examined doping of stoichiometric composition of tungsten (W) on this system to increase bulk and interfacial conductivity while managing the contaminant generation of crystallographic defects and recombination sites. In this paper, a deep investigation was carried out to examine the effect of non-stoichiometric W doping in BiVO4 system. Stoichiometric and non-stoichiometric W-doped monoclinic BiVO4 (i.e. Bi1-(xtd)V1-xWxtdO4; BiV1-xWxtdO4 and BiV1-yWyO4; x ? 0.008; y ? 0.03 and d ? 0.005) were prepared using a facile dip coating technique. The stoichiometric composition contains charge balanced Bi, V and W atoms whereas non-stoichiometric compositions contain excess Bi and excess Bi and W. The non-stoichiometric composition BiV1-xWxtdO4 has shown better photoelectrochemical water splitting performance with respect to other compositions at 1.23 V vs RHE, under one sun illumination of electrode. The XRD and XPS results shows that non-stoichiometric doping with excess Bi or with excess Bi and W can possibly create an environment where V5t ions are substitutional replaced by W6t ions without generating other defects. But there was no signi?cant difference in band gap of different compositional samples observed. Further electrochemical impedance technique was used to analyze change in bulk and surface charge mobility with W-doping in BiVO4. The electrochemical impedance analysis showed the presence of low interfacial resistance, lower charge transfer resistance and high charge donor/surface state density for non-stoichiometric composition BiV1-xWxtdO4 electrode. It is evident from and cyclic voltammetry that the addition of excess Bi and W from its stoichiometric quantity ef?ciently suppressed the formation of hole-electron pair recombination sites. The electrochemical analytical results lead us to believe that the particular non-stoichiometric composition of BiV1-xWxtdO4 can signi?cantly lower trap sites and enhances kinetics of charge transfer, leading to the better photoelectrochemical water splitting performance.
关键词： Oxygen evolution,Photoelectrochemical cell,Water splitting,Bismuth vanadate,Tungsten doping
更新于2025-09-23 15:23:52
-
Photocatalytic overall water splitting on isolated semiconductor photocatalyst sites in an ordered mesoporous silica matrix: A multiscale strategy
摘要： Photocatalytic overall water splitting (OWS) in a stoichiometric ratio has attracted increasing attention for the realization of a sustainable, environmentally friendly future. However, this reaction exhibits sluggish kinetics due to efficiency limitations of the involved steps, including photon absorption, electron transfer, and the reactions that occur at triple-phase boundary regions. Herein, we report a general multiscale strategy to address this challenge by designing a model composite catalyst with a high loading density of isolated Bi0.5Y0.5VO4 nanocrystals, as building blocks, dispersed in a hexagonally ordered mesoporous silica matrix. In contrast to the well-recognized heterojunction formed between different semiconductors, we show that confined growth favours the formation of isolated quaternary solid-solution photocatalysts (Bi0.5Y0.5VO4), which can further interface with the insulating silica to overcome temperature limitations and exhibit enhanced photon absorption and electrochemical and mass transfer properties due to the transparent periodic porous structure of silica and the as-formed small nanocrystals with high crystallinity and a passivated surface. When the semiconductor photocatalyst is incorporated with the inert silica insulator, this nanoarchitecture does not inhibit the OWS activity but actually delivers a 10-fold higher OWS activity than bulk Bi0.5Y0.5VO4 prepared by the conventional solid-state method.
关键词： Multiscale strategy,Photocatalysis,Isolated solid-solution nanocrystal,Overall water splitting,Mesoporous composite
更新于2025-09-23 15:23:52
-
Synthesis and annealing process of ultra-large SnS nanosheets for FTO/SnS/CdS/Pt photocathode
摘要： SnS has been widely used in photoelectric devices due to its special band gap of 1.2–1.5 eV. Here, we reported on the fabrication of SnS nanosheets and the effect of synthesis condition together with heat treatment on its physical properties. The obtained band gap of the SnS nanosheets is in the rage of 1.37–1.41 eV. It was found that the photo-current density of a thin film comprised of SnS nanosheets could be enhanced significantly by annealing treatment. The maximum photo-current density of the stack structure of FTO/SnS/CdS/Pt was high as 389.5 μA cm-2, rendering its potential application in high efficiency solar hydrogen production.
关键词： SnS nanosheets,Water splitting,Photoelectrochemical properties
更新于2025-09-23 15:23:52
-
Modulated anodization synthesis of Sn-doped iron oxide with enhanced solar water splitting performance
摘要： Modulated anodization synthesis is introduced here for the fabrication of porous Sn-doped iron oxide. Continuous square-wave modulation consisting of highly positive (+50 to +80 V range) and slightly negative potentials (-2 to -10 V range) at 100 Hz allowed the etching anodization of the metallic Fe foil and incorporation of Sn-dopant from the fluoride anion-containing electrolyte, respectively. Compared with the undoped iron oxide, the surface-enriched Sn-dopant (in the form of Sn4+) alleviates the trapping and recombination of surface holes, while enhancing the hole transfer at the surface states. As such, the overpotential for photoelectrochemical (PEC) water oxidation was reduced by 110 mV and photocurrent density doubled. The incorporation of Co-Pi co-catalyst further improved the hole transfer efficiency, resulting in further reduction in overpotential by another 330 mV with respect to the bare Sn-doped iron oxide and significant improvement in photocurrent density at potentials below +1.23 V vs. reversible hydrogen electrode. Lastly, the iron oxide electrodes exhibit highly stable PEC water oxidation with no degradation in activity throughout the 10 h assessment under simulated solar irradiation and Faradaic efficiency of 90%. We envisage that the modulated anodization technique can be conveniently incorporated for a wide range of other dopants in search of efficient solar water splitting electrodes.
关键词： Doping,Hematite,Hydrogen,Photoelectrochemical water splitting,Charge transport
更新于2025-09-23 15:23:52
-
Elucidation of the structural and charge separation properties of titanium-doped hematite films deposited by electrospray method for photoelectrochemical water oxidation
摘要： Elemental doping is considered to be an effective strategy to improve the photoelectrochemical (PEC) activity of hematite (a-Fe2O3) as a photoanode for water splitting, but the precise function(s) of the dopant remains unclear. In this study, we report on the structural and charge separation properties of titanium-doped hematite (Ti doped Fe2O3) films prepared by a simple electrospray technique for PEC water oxidation. The effect of Ti doping on the structure, morphology, light absorption, and electrical and photoelectrochemical properties was investigated on a-Fe2O3 films. SEM images revealed a reduction in particle sizes for 2% Ti doped a-Fe2O3, while an increase in particle size was observed for higher Ti content. XRD confirmed the presence of a-Fe2O3 without any impurity or other phases. From XPS spectra, the incorporation of Ti was confirmed in the form of Ti4+ as predominant species while no impurities from the substrate were detected. When the Ti doped Fe2O3 (2% Ti) film was used as a photoanode in a PEC cell, it delivered the best performance with a maximum photocurrent density of 1.09 mA cm-2 (at 1.8 V vs. RHE and under standard 1 sun illumination conditions (AM 1.5 G, 100 mW cm-2)), which is 2 times higher than that of the un-doped a-Fe2O3 (0.51 mA cm-2). The photoelectrode also showed a superior incident photon to current efficiency (IPCE) as compared to an un-doped a-Fe2O3. This enhancement in performance was attributed to the better charge separation and transport properties of a-Fe2O3 due to Ti doping, as revealed by an electrochemical impedance spectroscopy (EIS) analysis.
关键词： Electrospray deposition,PEC,a-Fe2O3,Ti doping,Water splitting
更新于2025-09-23 15:23:52
-
Oxynitride Thin Films versus Particle-Based Photoanodes: a Comparative Study for Photoelectrochemical Solar Water Splitting
摘要： The solar water splitting process assisted by semiconductor photocatalysts attracts growing research interests worldwide for the production of hydrogen as a clean and sustainable energy carrier. Due to their optical and electrical properties several oxynitride materials show great promise for the fabrication of efficient photocatalysts for solar water splitting. This study reports a comparative investigation of particle- and thin films-based photocatalysts using three different oxynitride materials. The absolute comparison of the photoelectrochemical activities favors the particle-based electrodes due to the better absorption properties and larger electrochemical surface area. However, thin films surpass the particle-based photoelectrodes due to their more suitable morphological features that improve the separation and mobility of the photo-generated charge carriers. Our analysis identifies what specific insights into the properties of materials can be achieved with the two complementary approaches.
关键词： Oxynitride,pulsed laser deposition,photoelectrochemistry,thin films,solar water splitting,photoanode
更新于2025-09-23 15:23:52
-
Organic/inorganic nitride heterostructure for efficient photocatalytic oxygen evolution
摘要： Given the four-electron water oxidation reaction as the rate-limiting step for water splitting, highly efficient photocatalysts for oxygen evolution have been receiving increasing research attentions. In this study, an organic/inorganic g-C3N4/CoN nitride heterostructure was developed by a facile precipitation-nitridation two-step process. With the CoN loading amounts optimized, the obtained g-C3N4/CoN composite achieves more than 4-fold increase in photocatalytic activity for oxygen evolution, as compared to the pristine g-C3N4, with a highest oxygen evolution rate reaching 607.2 μmol h?1 g?1 under visible light (λ > 420 nm). It was demonstrated that the formed g-C3N4/CoN heterostructure could promote the interfacial charge carrier separation and the loaded CoN acting as an effective cocatalyst could accelerate the water oxidation reaction kinetics, which synergistically contributes to the great enhancement in photocatalytic activity for oxygen evolution. Interestingly, by physically mixing g-C3N4/CoN and g-C3N4/Ni, acting as oxygen and hydrogen production photocatalysts, respectively, the obtained composite could stably produce oxygen and hydrogen in the stoichiometric ratio from pure water under visible light (λ > 420 nm). Although the photocatalytic overall water splitting activity is still very low, this study demonstrates a facile and promising approach to develop visible-light active photocatalysts for simultaneous hydrogen and oxygen production from water, from the perspective of surface modification and bifunctional cocatalyst loading.
关键词： Oxygen evolution,g-C3N4,Photocatalytic water splitting,Heterostructures
更新于2025-09-23 15:23:52
-
Constructing 3D sub-micrometer CoO octahedrons packed with layered MoS2 shell for boosting photocatalytic overall water splitting activity
摘要： A 3D architectures of CoO@MoS2 composite photocatalyst was prepared by coating MoS2 onto the (1 1 1) facts of sub-micrometer CoO octahedrons via a facile solvothermal method. The CoO@MoS2 composites show a significantly improved photocatalytic activity for overall water splitting. At an optimal ratio of 3 wt% MoS2, CoO@MoS2-3% composite can split pure water with the stoichiometric ratio production of H2 and O2 under visible light irradiation, meanwhile, presents the highest H2 production evolution (1.07 μmol/h), which is almost four times than that of pure CoO (0.26 μmol/h). Moreover, the CoO@MoS2 composite still remains good stability after three successive cyclings (over 72 h). The enhanced photocatalytic activity and stability can be attributed that the layered MoS2 shell not only promoted the photo-induced charge transfer at the interface of CoO due to the sufficient contact area between CoO and MoS2, but also protected the exposed the (1 1 1) facts of CoO from devastation. Our work offers more insights into the development of a simple synthesis of well-shaped 3D-based composite photocatalysts towards the energy- and environmental-related applications.
关键词： CoO octahedrons,MoS2,Overall water splitting,Core-shell,Visible light
更新于2025-09-23 15:23:52