Two-Step Process of a Crystal Facet-Modulated BiVO4 Photoanode for Efficiency Improvement in Photoelectrochemical Hydrogen Evolution

Synergistic Effect of Topological Semimetal TiSi and Plasmonic Cu for Enhanced Photoelectrocatalytic Water Splitting of TiO2 Nanorod Array

Developing high-efficiency and low-cost catalysts for PEC water splitting is vital for solving the issues of energy consumption, environmental pollution, and global warming. In this study, we designed and prepared a composite photoanode TiO2/TiSi/Cu by depositing a topological semimetal TiSi film and plasmonic Cu nanoparticles onto a TiO2 nanorod array. Due to the synergistic effect of the topological bands of TiSi and the SPR effect of Cu, TiO2/TiSi/Cu exhibits significantly enhanced optical absorption in the visible-light region. Under wavelength (λ) > 420 nm light irradiation, the photocurrent density of TiO2/TiSi/Cu reaches 4.46 mA cm-2 at 1.9 V vs RHE, about 17.84 times that of pure TiO2. The carrier lifetime is prolonged from 25.04 ns for pure TiO2 to 31.13 ns for TiO2/TiSi/Cu. Furthermore, the TiO2/TiSi/Cu photoanode demonstrates good long-term cyclic stability, with an average hydrogen production rate of 8.12 μmol cm-2 h-1. Our results indicate that the synergistic effect of topological semimetal TiSi and plasmonic Cu is an effective strategy to enhance the PEC performance of TiO2. This approach could be applied to other topological catalysts, providing new opportunities for developing novel and efficient catalysts.

Enhancing Photoelectrochemical Seawater Splitting Efficiency by a Dual-Strategy Approach of W Doping and CoOOH Layer Deposition on BiVO4 Photoanodes

Photoelectrochemical (PEC) seawater splitting offers a sustainable pathway for hydrogen production, yet its practical application is hindered by sluggish reaction kinetics and severe photocorrosion in chloride-rich environments. This study presents a dual-strategy modification of BiVO4 photoanodes through tungsten (W) doping and cobalt oxyhydroxide (CoOOH) nanolayer deposition to synergistically enhance the PEC performance and stability in natural seawater. W doping optimizes the electronic structure of BiVO4 by reducing the bandgap from 2.4 to 2.35 eV and increasing carrier concentration from 1.41 × 1021 to 3.31 × 1021 cm-3, while CoOOH acts as a dual-functional layer that suppresses surface recombination via oxygen vacancy formation and protects against chloride-induced corrosion. The optimized CoOOH/W-BVO photoanode achieves a photocurrent density of 3.77 mA cm-2 at 1.23 V vs reversible hydrogen electrode (RHE) with 96 h stability in natural seawater, outperforming pristine BiVO4 by 150% and single-modified counterparts by 40-60%. Mechanistic analyses reveal that W6+ substitution elongates V-O bonds, thereby enhancing the bulk charge separation. Concurrently, CoOOH facilitates hole extraction through oxygen vacancies, with oxygen vacancy content increasing from 3.9% to 24.3%. The dual modification also reduces interfacial charge-transfer resistance to 94.44 Ω and shifts the flat-band potential negatively to 0.15 V vs RHE, improving light absorption and charge utilization efficiency (applied bias photocurrent efficiency (ABPE) of 0.95% at 0.77 V). This work provides a robust strategy for designing efficient and durable photoanodes, advancing marine-resource-utilized renewable energy technologies.

Construction of Ultrathin BiVO4-Au-Cu2O Nanosheets with Multiple Charge Transfer Paths for Effective Visible-Light-Driven Photocatalytic Degradation of Tetracycline

In this study, unique BiVO4-Au-Cu2O nanosheets (NSs) are well designed and multiple charge transfer paths are consequently constructed. The X-ray photoelectron spectroscopy measurement during a light off-on-off cycle and redox capability tests of the photo-generated charge carriers confirmed the formation of Z-scheme heterojunction, which can facilitate the charge carrier separation and transfer and maintain the original strong redox potentials of the respective component in the heterojunction. The ultrathin 2D structure of the BiVO4 NSs provided sufficient surface area for the photocatalytic reaction. The local surface plasmon resonance (LSPR) effect of the electron mediator, Au NPs, enhanced the light absorption and promoted the excitation of hot electrons. The multiple charge transfer paths effectively promoted the separation and transfer of the charge carrier. The synergism of the abovementioned properties endowed the BiVO4-Au-Cu2O NSs with satisfactory photocatalytic activity in the degradation of tetracycline (Tc) with a removal rate of ≈80% within 30 min under visible light irradiation. The degradation products during the photocatalysis are confirmed by using ultra-high performance liquid chromatography-mass spectrometry and the plausible degradation pathways of Tc are consequently proposed. This work paves a strategy for developing highly efficient visible-light-driven photocatalysts with multiple charge transfer paths for removing organic contaminants in water.

Enhancement of charge separation and hole utilization in a Ni2P2O7-Nd-BiVO4 photoanode for efficient photoelectrochemical water oxidation

It is necessary for photoelectrochemical (PEC) water splitting to reduce the electron-hole recombination rate and enhance the water oxidation reaction kinetics. Here, we prepared Ni₂P₂O₇-Nd-BiVO₄ composite photoanodes by coupling Ni₂P₂O₇ co-catalysts to neodymium (Nd)-doped BiVO₄ surfaces through photo-assisted electrodeposition. The Ni₂P₂O₇-Nd-BiVO₄ photoanode exhibits a high photocurrent density of 3.6 mA cm^-2 at 1.23 V vs reversible hydrogen electrode (RHE), which is three times higher than that of the bare BiVO₄ (1.2 mA cm^-2). Detailed characterizations demonstrate that Nd doping reduces the band gap, significantly increases the carrier density and effectively reduces the charge transfer resistance. More importantly, the Ni₂P₂O₇ co-catalyst has multiple roles. Specifically, it can act as a hole extraction layer to accelerate hole migration and inhibit hole-electron recombination. At the same time, it significantly improves the water oxidation reaction kinetics. In addition, it also provides more water oxidation active sites. This work provides ideas for the design and study of efficient BiVO₄-based photoanodes.