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Hierarchical Ta-Doped TiO2 Nanorod Arrays with Improved Charge Separation for Photoelectrochemical Water Oxidation under FTO Side Illumination
摘要： TiO2 is one of the most attractive semiconductors for use as a photoanode for photoelectrochemical (PEC) water oxidation. However, the large-scale application of TiO2 photoanodes is restricted due to a short hole diffusion length and low electron mobility, which can be addressed by metal doping and surface decorating. In this paper we report the successful synthesis of hierarchical Ta doped TiO2 nanorod arrays, with nanoparticles on the top (Ta:TiO2), on F-doped tin oxide (FTO) glass by a hydrothermal method, and its application as photoanodes for photoelectrochemical water oxidation. It has been found that the incorporation of Ta5+ in the TiO2 lattice can decrease the diameter of surface TiO2 nanoparticles. Ta:TiO2-140, obtained with a moderate Ta concentration, yields a photocurrent of ～1.36 mA cm?2 at 1.23 V vs. a reversible hydrogen electrode (RHE) under FTO side illumination. The large photocurrent is attributed to the large interface area of the surface TiO2 nanoparticles and the good electron conductivity due to Ta doping. Besides, the electron trap-free model illustrates that Ta:TiO2 affords higher transport speed and lower electron resistance when under FTO side illumination.
关键词： hierarchical TiO2,photoelectrochemical water oxidation,Ta doping,charge separation
更新于2025-09-09 09:28:46
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Charge separation and ROS generation on tubular sodium titanates exposed to simulated solar light
摘要： The research focuses on a few key points concerning the light-driven processes taking place on TiO2 anatase and sodium titanates with tubular morphology, such as the relationship between the morphology and activity for H2 and CO2 production, density of surface hydroxyl groups, ROS (?OH and ?O2-) production and photocatalytic activity, and charge separation at the interface of semiconducting domains and enhancement of activity. One key point discussed is whether the materials with peculiar morphologies (i.e. tubular) are superior to the conventional ones. The experimental evidences show that the main advantage of the tubular morphology of sodium titanate is given by its significantly higher surface area compared to parental anatase. FTIR and XPS progressive analyses evidence that the density of surface hydroxyl groups decreases with the development of the tubular morphology. The radical trapping experiments show that the variation of surface hydroxyl density is, generally, followed by activities for ?OH and ?O2- generation, as well as by the photocatalytic production of H2 and CO2 from water/methanol mixture. Consequently, the ROS, formed by action of photogenerated electrons and holes on adsorbed O2 and hydroxyl groups, respectively, play an important role in determining the photocatalytic activity of titania-based materials. The other major aspect revealed by this research is that the charge separation at the interfaces formed between anatase and sodium titanate crystalline phases has remarkable effect on the activity formation rates of H2 and CO2.
关键词： titanate nanotubes,reactive oxygen species,charge separation,simulated solar light,photocatalysis
更新于2025-09-09 09:28:46
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KOH-Modified Ni/LaTiO2N Schottky Junction Efficiently Reducing CO2 to CH4 under Visible Light Irradiation
摘要： Efficiency of solar-driven CO2 into fuels is largely limited by the sluggish reaction kinetics resulting from high activation barriers and poor electron-hole separation. Here, a synergistic strategy was proposed to overcome these obstacles. As a prototype, KOH-modified Ni/LaTiO2N photocatalyst afforded a high performance in CO2 reduction with a generation rate of 9.69 μmol g-1 for CH4 and 0.31 μmol g-1 for CO, about 5 times higher than the catalytic activities of LaTiO2N. The prominent enhancement results in the following effects: (1) Schottky barrier at Ni/LaTiO2N interface boosts separation of electron-hole pairs. (2) The OH- of KOH as basic sites favors activation of CO2 into CO3 2- species, significantly improving the reaction kinetics of CO2 reduction. (3) The OH- also functions as hole acceptor, boosting the proton release from H2O oxidation.
关键词： molecule activation,Schottky junction,CO2 reduction,charge separation
更新于2025-09-09 09:28:46
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C(sp <sup>3</sup> )-H Bond Activation by Perovskite Solar Photocatalyst Cell
摘要： Inspired by the efficient perovskite solar cells, we developed a three-component hybrid perovskite-based solar photocatalyst cell - NiOx/ FAPbBr3/TiO2 - for C(sp3)-H bonds activation with high selectivity (~90%) and high conversion rates (3800 μmol g-1 h-1) under ambient conditions. Time-resolved spectroscopy on our photocatalytic cell reveals efficient exciton dissociation and charge separation, where TiO2 and NiOx serve respectively as the electron and hole transporting layers. The photo-generated charge carriers, injected into TiO2 and NiOx drive the challenging C-H activation reaction via the synergetic effects of their band alignment relative to FAPbBr3. The reaction pathway is investigated by controlling the free radical formation and we find that C-H activation is mainly triggered by hole oxidation. Besides aromatic alkanes, also C(sp3)-H bond in cycloalkanes can selectively be oxidised. This work demonstrates a generic strategy for engineering high-performance photocatalysts based on the perovskite solar cell concept.
关键词： photocatalysis,perovskite solar cells,charge separation,C(sp3)-H bond activation,selective oxidation
更新于2025-09-09 09:28:46
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Nontopological Transformation of Hierarchical TiO2 by Self-regulated Etching and Capping Roles of F- for Photocatalytic H2 Evolution
摘要： In the past decade, crystal facet engineering of TiO2 though various controllable strategies has attracted a lot of attention due to its strong facet dependent photoactivities. In this work, we report on nontopological transformation of titanium oxydifluoride (TiOF2) to hierarchical TiO2 structures by hydrothermal tailoring. The fluorine-containing species in TiOF2 crystal perform the roles as either an etching agent or a capping agent, which can conveniently modulate morphologies and facets of TiO2 crystals via dissolution or oriented collapse under hydrothermal condition. The Wulff construction and different surface energies of shape and facet lead to the controlled formation of hierarchical TiO2, respectively with (101) faceted nanowalls, (001) and (111) faceted nanosheets, or their multi-facets. All TiO2 with single exposed facet exhibit higher photocatalytic H2 evolution performance than the commercial P25 TiO2. Moreover, the (101) faceted nanowalls demonstrate superior photocatalytic H2 evolution to (111) and (001) faceted TiO2 nanosheets in presence of hole scavenger (methanol) due to favoured hole transfer at (101) facet/methanol interface. This work presents novel methodology for shape and facet control of TiO2 towards solar to fuel conversion.
关键词： Charge separation,H2 evolution,Oriented collapse,Facet Engneering,Dissolution
更新于2025-09-04 15:30:14
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Stable, carrier separation tailorable conjugated microporous polymers as a platform for highly efficient photocatalytic H2 evolution
摘要： The molecular design of highly photo-functional polymers with high charge separation efficiency and wide spectral absorption are long term quest for photocatalysis. Herein, we design and develop a series of nitrogen-containing conjugated microporous polymers (N-CMPs) with tailored donor-acceptor units for enhancing charge separation and light harvesting for visible light photocatalytic H2 production. By alternating the substitution position (o-, m-, or p-) and the number of electron donor (carbazole, diphenylamine) and acceptor (cyano) units on the 3D-core structure, a series of N-CMPs with adjustable donor-acceptor (D-A) charge separation efficiencies and tuneable band gaps in the range of 1.64-2.29 eV were obtained, enabling the precise control of the photocatalytic activity at the molecular level. The optimized N-CMP (4-CzPN) exhibits a higher visible light H2 production rate at 2103.2 μmol/h·g and the apparent quantum yield (AQY) at 420 nm reaches 6.4%. Furthermore, the 4-CzPN photocatalyst maintains excellent durability and recycling performance under 25 h continued light irradiation. The outstanding photocatalytic performance of the optimized N-CMPs with D-A structure is attributed to the enhanced polarity and conjugated degree of their core structure, which promotes charge separation and light absorption.
关键词： light absorption,donor-acceptor units,photocatalytic H2 production,conjugated microporous polymers,charge separation
更新于2025-09-04 15:30:14
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Tuning CuOx-TiO2 interaction and photocatalytic hydrogen production of CuOx/TiO2 photocatalysts via TiO2 morphology engineering
摘要： CuOx/TiO2 photocatalysts prepared with anatase TiO2 nanocrystals exposing different types of facets as supports were examined for photocatalytic H2 production in methanol/water solution under simulated solar light. Catalyst structures were characterized by XRD, HRTEM, XPS, UV–vis, EPR, PL, H2-TPR and CO chemisorption. Enhanced photocatalytic H2 productions of CuOx/TiO2 photocatalysts followed an order of CuOx/TiO2-{001} > CuOx/TiO2-{100} > CuOx/TiO2-{101}. TiO2 facets were found to strongly affect the CuOx-TiO2 interaction and structures of CuOx/TiO2 photocatalysts. Cu2O-TiO2 interaction in CuOx/TiO2-{001} photocatalyst is the strongest, resulting in the highest Cu2O dispersion and density of Cu2O-TiO2 heterojunctions active in photocatalytic H2 production. The results add insights into morphology engineering as an effective strategy to tune structures and photocatalytic activity of TiO2-based composite photocatalysts.
关键词： metal-support interaction,water reduction,charge separation,photocatalysis,facet
更新于2025-09-04 15:30:14
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Band structure tuning and charge separation of MNX monolayers and MNX/GaS van der Waals heterostructures
摘要： Efficient charge separation and band structure tuning are very important for application to photoelectric device. Here, based on first-principles calculations, we propose two-dimensional (2D) MNX (M=Zr, Hf; X=Cl, Br, I) monolayers which can be exfoliated from the corresponding layered bulk phase due to the low cleavage energy. The phonon band structure and the mechanical analysis indicate that 2D MNX monolayers can form free-standing membranes. The calculated results suggest that 2D MNX monolayers are indirect band gap semiconductors with band gaps in the range of 1.55-3.37 eV. Among them, MNI (M=Zr, Hf) monolayers with effective charge separation and moderate band gaps would have potential application to photocatalytic water splitting. In order to realize the effective charge separation for the other MNX monolayers, MNX/GaS (X=Cl, Br) heterostructures are investigated. Our calculations reveal that MNX/GaS heterostructures are typical type-II band alignment, facilitating the separation of photogenerated carriers where electrons and holes are localized in MNX and GaS monolayers, respectively. Furthermore, the band gaps of the MNX/GaS heterostructures are obviously narrowed compared to those of the isolated constituent monolayers. In addition, the band gaps and band edge positions of MNX/GaS heterostructures can further be tuned by biaxial strain to match better with the redox potentials of water. These findings in this study not only enrich the family of 2D materials, but also demonstrate that MNI (M=Zr, Hf) monolayers and MNX/GaS heterostructures are promising candidates for photocatalytic materials.
关键词： van der Waals heterostructures,photocatalytic water splitting,band structure tuning,MNX monolayers,charge separation
更新于2025-09-04 15:30:14
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Metal–Organic Frameworks for Photocatalysis and Photothermal Catalysis
摘要： To meet the ever-increasing global demand for energy, conversion of solar energy to chemical/thermal energy is very promising. Light-mediated catalysis, including photocatalysis (organic transformations, water splitting, CO2 reduction, etc.) and photothermal catalysis play key roles in solar to chemical/thermal energy conversion via the light?matter interaction. The major challenges in traditional semiconductor photocatalysts include insufficient sunlight utilization, charge carrier recombination, limited exposure of active sites, and particularly the difficulty of understanding the structure?activity relationship. Metal?organic frameworks (MOFs), featuring semiconductor-like behavior, have recently captured broad interest toward photocatalysis and photothermal catalysis because of their well-defined and tailorable porous structures, high surface areas, etc. These advantages are beneficial for rational structural modulation for improved light harvesting and charge separation as well as other effects, greatly helping to address the aforementioned challenges and especially facilitating the establishment of the structure?activity relationship. Therefore, it is increasingly important to summarize this research field and provide in-depth insight into MOF-based photocatalysis and photothermal catalysis to accelerate the future development.
关键词： Charge separation,Photocatalysis,Light harvesting,Solar energy conversion,Photothermal catalysis,Metal?organic frameworks
更新于2025-09-04 15:30:14