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A multiphase BiVO4 with the potential of being an environmental photocatalyst
摘要： Novel Y3+ and Mo6+ dual-doped, multiphased BiVO4 nanoparticles (NPs) were synthesised using a modified hydrothermal method through a gradient doping method. Yttrium (III) was used as a phase-stabilising agent for the tetragonal phase, while Mo6+ was used to control the volume of the crystals. The NPs were characterised using SEM, TEM, PL, FTIR, XRD, and BET to determine crystal phase, morphology, and surface area. It was found that the introduction of the dopants and formation of the phase junction lead to diminished PL spectra indicative of reduced electron–hole recombination. The 10% (m–m) Y–Mo dual-doped multiphased BiVO4 NPs have the highest electron–hole separation efficiency. However, 15% (m–m) Y–Mo had the least charge separation due to the formation of recombination centres at high degrees of metal doping. The multiphased systems also showed a red shift in the UV–Vis absorption spectrum. The Mott–Schottky plot obtained from electroimpedance spectroscopy confirmed the formation of a phase junction in the multiphased systems which resulted in an improvement of the photocurrent to twice that of the intrinsic BiVO4 NPs for the 10% Y–Mo BiVO4 NPs. The photocurrent for 10% Y–Mo was 0.025 A cm?2, while that of the intrinsic BiVO4 NPs was about 0.014 A cm?2. This increase in photocurrent proves the improvement of charge separation. BET results showed that surface area increased with an increase in the degree of doping and that the 10% Y–Mo dual-doped BiVO4 nanomaterials had a surface area of 9.009 m2/g. The 10% Y–Mo dual-doped BiVO4 reached 99.1% Cr6+ removal in 60 min.
关键词： Charge separation,Phase stabilisation,Multiphase BiVO4
更新于2025-09-23 15:23:52
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Efficient separation of photo-generated charges in a ferroelectric molecular wire: nonadiabatic dynamics study on 3,5-dicyano-1,7-dimethylopyrrolo[3,2-f]indole trimer
摘要： In this work we propose and verify computationally a novel idea of spontaneous separation of charges photo-generated in a highly polar molecular 'wire'. The nuclear and electronic structure of the investigated system, so as the evolution of charge carriers, are characterized at the semi-empirical OM2/MRCI level of theory. Results point to the conclusion that 90% of optically prepared excitons break into charge carriers (holes and electrons) localized on the opposite monomeric units of the trimer on the time scale of 30 fs. Our findings can be helpful in design of photoactive and conducting components for molecular photovoltaic applications.
关键词： ferroelectric polymers,nonadiabatic molecular dynamics,molecular photovoltaics,photo-generated charge separation,molecular wire
更新于2025-09-23 15:22:29
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A Photoresponsive Rutile TiO <sub/>2</sub> Heterojunction with Enhanced Electron-Hole Separation for High-Performance Hydrogen Evolution
摘要： Rutile titanium dioxide (TiO2) is a promising photocatalyst due to its high thermodynamic stability and few intragrain defects. However, it has not yet achieved photocatalytic activity comparable to that of anatase TiO2 owing to its higher recombination rate of electron–hole pairs. To effectively separate the electron–hole pairs in rutile TiO2, a facet heterojunction (FH) structure to prolong the lifetime of the photogenerated electrons is proposed. Ultrathin TiO2 nanosheets with different facets are coated in situ onto TiO2 nanorod (NR) substrates, where FHs are built among the nanosheets as well as between the nanosheets and NR substrates. The as-prepared rutile TiO2, with an FH structure (FH-TiO2), serves as an effective photocatalyst for water splitting. More than 45 and 18 times higher photogenerated current density and H2 production rate, respectively, are obtained compared to those of pure rutile TiO2 NRs. Moreover, FH-TiO2 delivers a 0.566 mmol g?1 h?1 H2 production rate even in pure water. This study offers important insights into the rational design of rutile TiO2 structures for highly efficient photocatalytic reactions.
关键词： charge separation,rutile TiO2,facet heterojunction,water splitting
更新于2025-09-23 15:22:29
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Acid-treated Ti4+ doped hematite photoanode for efficient solar water oxidation—Insight into surface states and charge separation
摘要： Acid-treatment has been proved to be an efficient approach to improve the photoelectrochemical (PEC) performance of hematite. However, efforts to optimize hematite photoanode have been limited by an inadequate understanding of the semiconductor surface. Here we make efforts to understand the microscopic charge separation processes of Ti4+ doped Fe2O3 photoanode before and after acid-treatment. Surface photovoltage (SPV) transient and the work function measurements directly reveal that acid-treatment leads to passivation of the surface states. Surface photovoltage (SPV) spectroscopic studies coupled to open-circuit photovoltage (OPV) measurements indicate that the surface states of hematite photoanode before acid-treatment result in the pinning of the Fermi level, which reduce the intensity of interfacial electric field at the semiconductor-electrolyte interface.
关键词： Water oxidation,Charge separation,Surface states,Hematite,Acid-treatment
更新于2025-09-23 15:22:29
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New method for improving the bulk charge separation of hematite with enhanced water splitting
摘要： Due to its poor bulk charge separation efficiency, the photoelectrochemical (PEC) performance of pristine hematite prepared directly from an electrodeposited Fe film is limited. Au-modification of hematite via a simple immersion method improves the PEC performance two-fold to 0.31 mA cm?2. The Au nanoparticles deposited from HAuCl? act as plasmonic photosensitizers and electron collectors to improve the light absorption and bulk charge separation efficiency of the photoanode. In addition, the increase in the (110) plane and specific surface area induced by HAuCl? enhances the bulk charge separation efficiency. After further modification with Ti, the photocurrent response of the resulting Ti/Au/α-Fe?O? photoanode improves to 0.51 mA cm?2; this increase is attributed to its increased light absorption, bulk charge separation efficiency (η_bulk), and surface charge injection efficiency (η_surface). In this work, the effect of Au and Ti on the crystalline structure, morphology and PEC performance of the novel electrodeposited hematite photoanode are investigated by systematical characterization.
关键词： Cathodic electrodeposition,Hematite,Charge separation,Modification,Au nanoparticles
更新于2025-09-23 15:22:29
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Electron Diffusion Length and Charge Separation Efficiency in Nanostructured Ternary Metal Vanadate Photoelectrodes
摘要： Ternary metal vanadates have recently emerged as promising photoelectrode materials for sunlight-driven water splitting. Here, we show that highly active nanostructured BiVO4 films can be deposited onto fluorine-doped tin oxide (FTO) substrates by a facile sequential dipping method known as successive ionic layer adsorption and reaction (SILAR). After annealing and deposition of a cobalt phosphate (Co-Pi) co-catalyst, the photoelectrodes produce anodic photocurrents (under 100 mW cm-2 broadband illumination, 1.23 V vs. RHE) in pH 7 phosphate buffer that are on par with the highest reported in the literature for similar materials. To gain insight into the reason for the good performance of the deposited films, and to identify factors limiting their performance, incident photon-to-electron conversion efficiency spectra have been analyzed using a simple diffusion–reaction model to quantify the electron diffusion length (Ln; the average distance travelled before recombination) and charge separation efficiency (ηsep) in the films. The results indicate that ηsep approaches unity at sufficiently positive applied potential but the photocurrent is limited by significant charge collection losses due to a short Ln relative to the film thickness. The Co-Pi catalyst is found to improve ηsep at low potentials as well as increase Ln at all potentials studied. These findings help to clarify the role of the Co-Pi co-catalyst and show that there could be room for improvement of BiVO4 photoanodes deposited by SILAR if Ln can be increased.
关键词： charge separation efficiency,ternary metal vanadates,SILAR,electron diffusion length
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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Unique 1D Cd <sub/>1?</sub><i> <sub/>x</sub></i> Zn <i> <sub/>x</sub></i> S@O-MoS <sub/>2</sub> /NiO <i> <sub/>x</sub></i> Nanohybrids: Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Evolution via Integrated Structural Regulation
摘要： Development of noble-metal-free photocatalysts for highly efficient sunlight-driven water splitting is of great interest. Nevertheless, for the photocatalytic H2 evolution reaction (HER), the integrated regulation study on morphology, electronic band structures, and surface active sites of catalyst is still minimal up to now. Herein, well-defined 1D Cd1?xZnxS@O-MoS2/NiOx hybrid nanostructures with enhanced activity and stability for photocatalytic HER are prepared. Interestingly, the band alignments, exposure of active sites, and interfacial charge separation of Cd1?xZnxS@O-MoS2/NiOx are optimized by tuning the Zn-doping content as well as the growth of defect-rich O-MoS2 layer and NiOx nanoparticles, which endow the hybrids with excellent HER performances. Specifically, the visible-light-driven (>420 nm) HER activity of Cd1?xZnxS@O-MoS2/NiOx with 15% Zn-doping and 0.2 wt% O-MoS2 (CZ0.15S-0.2M-NiOx) in lactic acid solution (66.08 mmol h?1 g?1) is about 25 times that of Pt loaded CZ0.15S, which is further increased to 223.17 mmol h?1 g?1 when using Na2S/Na2SO3 as the sacrificial agent. Meanwhile, in Na2S/Na2SO3 solution, the CZ0.15S-0.2M-NiOx sample demonstrates an apparent quantum yield of 64.1% at 420 nm and a good stability for HER under long-time illumination. The results presented in this work can be valuable inspirations for the exploitation of advanced materials for energy-related applications.
关键词： charge separation,1D hybrid nanostructures,photocatalytic hydrogen evolution,band alignments,active sites
更新于2025-09-23 15:22:29
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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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Salt Effect in Ion-Pair Dynamics after Bimolecular Photoinduced Electron Transfer in a Room-Temperature Ionic Liquid
摘要： Bimolecular photoinduced electron transfer between perylene and two quenchers was investigated in an imidazolium room-temperature ionic liquid (RTIL) and in a dipolar solvent mixture of the same viscosity using transient absorption on the subpicosecond to submicrosecond timescales. Whereas charge separation dynamics were similar in both solvents, significant differences were observed in the temporal evolution of the ensuing radical ions: although small, the free ion yield is significantly larger in the RTIL, and recombination of the ion pair to the triplet state of perylene is more efficient in the dipolar solvent. The temporal evolution of reactant, ion and triplet state populations could be well reproduced using Unified Encounter Theory. This analysis reveals that the observed differences can be explained by the strong screening of the Coulomb potential in the ion pair by the ionic solvent. In essence, RTILs favor free ions compared to highly dipolar solvents of the same viscosity.
关键词： unified encounter theory,free ions,spin conversion,charge recombination,transient absorption,charge separation
更新于2025-09-23 15:21:21