Tam Brian, Pike Sebastian D, Nelson Jenny, Kafizas Andreas
Department of Chemistry, Molecular Science Research Hub, Imperial College London White City London W12 0BZ UK
Department of Physics, Imperial College London South Kensington London SW7 2AZ UK.
Chem Sci. 2025 Apr 1;16(18):7794-7810. doi: 10.1039/d4sc08595g. eCollection 2025 May 7.
Due to their complementary absorption characteristics and band energy structure, the BiVO-coated WO heterojunction architecture is commonly employed as a metal oxide photoanode for the water oxidation half-reaction. The energy level ordering results in a staggered heterojunction that can effectively separate photoexcited electrons into the WO layer towards the current collector and photoexcited holes into the BiVO layer towards the interface with the electrolyte. Chemical vapour deposition (CVD) is an upscalable technique for fabricating large-area thin films of a wide range of semiconductors with nanoscale control. The fluorine-doped tin oxide (FTO)-coated transparent conductive glass substrates used herein are mass-produced by the glass industry with atmospheric pressure CVD and so the entire photoelectrode could be produced in one production process on float glass panels. This work is a detailed study of the use of atmospheric pressure CVD to fully-fabricate high-performance BiVO-coated WO nanostructures (500-2000 nm in length with 25-100 nm thick BiVO coatings) for photoelectrochemical (PEC) water splitting. Incident photon-to-current efficiency measurements were used to calculate optimal solar predicted photocurrents of 1.92 and 2.61 mA cm (2.3% and 3.2% solar-to-hydrogen efficiency if coupled to a hypothetical photovoltaic providing 1.23 V) for WO/BiVO heterojunction samples under front and back-illumination, respectively. The heterojunction showed more than additive improvements over the parent materials, with bare WO and BiVO samples showing 0.68 and 0.27 mA cm and 0.50 and 0.87 mA cm under front and back-illumination, respectively. Simulations of the current-voltage characteristics of tandem crystalline silicon photovoltaic modules coupled to the PEC devices were consistent with the solar predicted photocurrents. These promising results for BiVO-coated WO nanoneedles fully-deposited by atmospheric pressure CVD enables future research into photoanodes amenable to large-area scale-up.
由于其互补的吸收特性和能带结构，BiVO包覆的WO异质结结构通常被用作水氧化半反应的金属氧化物光阳极。能级排序导致形成交错异质结，该异质结可以有效地将光激发电子分离到朝向集电器的WO层中，并将光激发空穴分离到朝向与电解质界面的BiVO层中。化学气相沉积（CVD）是一种可扩展的技术，用于制造具有纳米级控制的各种半导体的大面积薄膜。本文中使用的氟掺杂氧化锡（FTO）包覆的透明导电玻璃基板是由玻璃行业通过常压CVD大规模生产的，因此整个光电极可以在浮法玻璃面板上通过一个生产过程制造出来。这项工作是对使用常压CVD来完全制造用于光电化学（PEC）水分解的高性能BiVO包覆的WO纳米结构（长度为500 - 2000 nm，BiVO涂层厚度为25 - 100 nm）的详细研究。入射光子到电流效率测量用于计算WO/BiVO异质结样品在正面和背面光照下的最佳太阳能预测光电流分别为1.92和2.61 mA/cm²（如果与提供1.23 V的假设光伏电池耦合，则太阳能到氢能效率分别为2.3%和3.2%）。该异质结相对于母体材料表现出超过相加的改进，裸WO和BiVO样品在正面和背面光照下分别显示出0.68和0.27 mA/cm²以及0.50和0.87 mA/cm²。耦合到PEC器件的串联晶体硅光伏模块的电流 - 电压特性模拟与太阳能预测光电流一致。通过常压CVD完全沉积的BiVO包覆的WO纳米针的这些有前景的结果使得未来能够对适合大面积放大的光阳极进行研究。
