Improvement in the photoelectrochemical (PEC) performance of WO₃/BiVO₄ heterojunction photoanodes is achieved by thermal treatment. The heterostructure systems consist of WO₃ and BiVO₄ layers spin coated onto fluorine‐doped tin oxide (FTO)‐coated glass substrates. The morphology and optical properties are modified by varying annealing conditions and calcining time. The crystal structure, morphology, and optical properties are studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis spectroscopy, respectively. The results show that the WO₃/BiVO₄ photoanodes obtain an interconnected structure which helps promote the PEC activity by increasing the active area for reaction and shortening the distance for carrier diffusion. Also, the preannealing treatment can improve film qualities, namely crystallinity, uniformity, and optical absorbance, leading to an enhancement of the PEC performance. The optimal thermal treatment is preannealing at 60 °C for 15 min, followed by calcining at 400 °C for 5 h. The photoanode with such an optimal treatment exhibits the highest photocurrent density under light‐emitting diode (LED) illumination, and the efficiency is increased by 3–4 times compared with the others. Herein, a simple method is offered to improve the PEC performance of a heterojunction photoelectrode.

中文翻译：

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通过热处理改善WO3 / BiVO4异质结薄膜光阳极的光电化学性能

通过热处理实现了WO ₃ / BiVO ₄异质结光电阳极的光电化学性能的提高。异质结构系统由旋涂在掺氟氧化锡（FTO）涂层的玻璃基板上的WO ₃和BiVO ₄层组成。通过改变退火条件和煅烧时间来改变形态和光学性质。分别使用X射线衍射（XRD），扫描电子显微镜（SEM）和紫外可见光谱研究了晶体的结构，形态和光学性质。结果表明，WO ₃ / BiVO ₄光阳极获得互连结构，该互连结构通过增加反应活性区域和缩短载流子扩散距离来帮助促进PEC活性。而且，预退火处理可以改善膜质量，即结晶度，均匀性和光吸收率，从而导致PEC性能的增强。最佳热处理是在60°C下预退火15分钟，然后在400°C下煅烧5小时。经过这种优化处理的光阳极在发光二极管（LED）照射下展现出最高的光电流密度，并且效率比其他阳极提高了3-4倍。这里，提供了一种简单的方法来改善异质结光电极的PEC性能。