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    压片与WO3处理协同促进电荷传输提升BiVO4光阳极性能

    Synergy of compression and WO3 treatment promotes charge transfer and enhances performance of BiVO4 photoanodes

    • 摘要: 颗粒粉末组装是一种简便、可规模化制备光电极的策略,但是所制备的光电极通常会面临颗粒间电荷传输不畅的问题。通过机械压片处理和WO3表面修饰显著提升了BiVO4光阳极的光电化学性能。首先采用水热法制备单斜相BiVO4粉末,通过滴涂法在掺氟氧化锡(Fluorine-doped Tin Oxide, FTO)基底上构建光阳极,并利用机械压片工艺增强颗粒间的电学接触与连接性。随后通过滴涂法在电极表面沉积一层WO3构建WO3/BiVO4复合电极,有效促进光生电荷分离并提供高效电子传输通道。结果表明:在AM 1.5 G光源(100 mW/cm2)照射下,经机械压片与WO3修饰后的BiVO4光阳极在2.0 V (相对于可逆氢电极)偏压下,光电流密度达到2.13 mA/cm2,而原始样品仅为0.28 mA/cm2,提升约7.8倍。单独机械压片和单独WO3修饰的光电流分别约为0.92、1.40 mA/cm2,表明两者协同效应显著。该复合光阳极同时表现出更高的电荷分离效率、载流子密度及催化活性,并具有良好的稳定性。本研究为高性能BiVO4基光阳极的设计与制备提供了新的优化策略。本研究将机械压片与化学表面修饰有机结合,前者解决了粉末组装电极固有的颗粒间断路问题,后者从能带角度优化了电荷分离与传输路径,两者协同实现远超单一处理的性能增益。该方法无需高温烧结或真空镀膜,避免晶粒长大和相变,且成本低廉、操作简便,适用于大面积制备。该策略不仅为BiVO4基光阳极提供了高效改进方案,也为其他颗粒型光电极(如WO3、TiO2)的性能优化提供了通用参考,对推动粉末组装技术在光电化学分解水领域的实际应用具有重要意义。

       

      Abstract: Particle powder assembly is a simple and scalable strategies for preparing photoelectrodes, but the photoelectrodes prepared by this method usually encounter the problem of poor charge transfer between particles. The photoelectrochemical performance of BiVO4 photoanodes was significantly improved through mechanical pressing treatment and WO3 surface modification. Firstly, monoclinic-phase BiVO4 powder was prepared by the hydrothermal method, and deposited onto fluorine-doped tin oxide (FTO) substrates by drop-casting to form the photoanode. The electrical contact and connectivity between particles were enhanced by the tablet pressing process. Subsequently, WO3 was deposited on the electrode surface to form a WO3/BiVO4 composite electrode, which effectively promoted the separation of photogenerated charges and provided an efficient electron transport channel. The results show that under AM 1.5G illumination (100 mW/cm2), the photoanode of BiVO4 after mechanical pressing and WO3 modification achieved a photocurrent density of 2.13 mA/cm2 at a bias of 2.0 V versus reversible hydrogen electrode (RHE), which was approximately 7.8 times higher than that of the original sample of 2.08 mA/cm2. The photocurrent densities obtained with either mechanical pressing alone or WO3 modification alone were about 0.92 and 1.40 mA/cm2, respectively, indicating a significant synergistic effect between the two treatments. The composite photoanode also exhibited higher charge separation efficiency, carrier density, and catalytic activity, and had good stability. This study provides a new optimization strategy for the design and preparation of high-performance BiVO4-based photoanodes. This work provides a novel optimization strategy for designing and preparing high-performance BiVO4-based photoanodes. By integrating mechanical pressing with chemical surface modification—where the former resolves the inherent interparticle discontinuities in powder-assembled electrodes and the latter optimizes charge separation and transport pathways from a band structure perspective—the combined approach achieves performance gains far exceeding those of individual treatments. The method avoids high-temperature sintering or vacuum coating, preventing grain growth and phase transformation, while being low-cost and easy to operate, making it suitable for large-scale fabrication. This strategy not only offers an effective enhancement route for BiVO4-based photoanodes but also serves as a general reference for optimizing other particulate photoelectrodes such as WO3 and TiO2, holding significant promise for advancing the practical application of powder-assembled technologies in photoelectrochemical water splitting.

       

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