光热效应增强BiVO4光阳极光电化学水分解性能研究

The photoelectrochemical (PEC) water splitting efficiency of BiVO4 photoanode is restricted by low photo-generated holes mobility and sluggish water oxidation kinetic. The temperature increase of BiVO4 photoanode can effectively solve these two problems. In this work, photoanode temperature will be increased via photothermal effect of the introduced photothermal material Co3O4 under near infrared light. As a result, photo-generated holes mobility and water oxidation kinetic of photoanode will be improved significantly, leading to a BiVO4 photoanode with highly efficient PEC water splitting efficiency. The main research contents are as follow: (1) Co3O4/Mo:BiVO4 photoanode will be prepared, and the photon-to-thermal conversion efficiency is controlled by adjusting the intensity of near infrared light and the loading amounts of Co3O4. The transport mechanism of photo-generated holes with the assistance of photothermal effect will be investigated. (2) Cocatalysts are further introduced to form NiOOH/FeOOH/Co3O4/Mo:BiVO4 photoanode. The relationship between photothermal effect and water oxidation kinetic of photoanode will be discussed. A highly efficient BiVO4 photoanode will be constructed with the assistance of photothermal conversion. The mechanism of enhanced PEC properties of BiVO4 photoanode induced by photothermal conversion will be clarified, which will provide a universal modification method to other photoanodes.

低的光生空穴迁移率及缓慢的水氧化动力学是制约BiVO4光阳极光电化学水分解性能的两个主要因素，BiVO4光阳极温度的提升能有效改善这两个问题。项目拟将光热材料Co3O4引入到光阳极，利用Co3O4在近红外光照射下的光热效应原位提高光阳极的温度，增强光生空穴迁移率的同时，促进表面的水氧化动力学，实现BiVO4光阳极高效的光电化学水分解效率。主要开展以下研究：（1）制备Co3O4/Mo:BiVO4光阳极，通过调节近红外光强度以及Co3O4的负载量调控光阳极的光热转换效率，探究光热辅助下光阳极光生空穴的传输机制。（2）进一步引入助催化剂，构建NiOOH/FeOOH/Co3O4/Mo:BiVO4光阳极，阐明光热效应与光阳极水氧化动力学之间的影响规律。借助光热转换，构筑高效的BiVO4光阳极；厘清光热效应增强BiVO4光阳极光电化学性能的内在机理，为其他光阳极的性能优化提供一种普遍适用的改性方法。

光电化学水分解是制备绿色氢气的一种有效方法。低的光生空穴迁移率及缓慢的水氧化动力学是制约BiVO4光阳极光电化学水分解性能的两个主要因素，BiVO4光阳极温度的提升能有效改善这两个问题。项目将光热材料Co3O4引入到光阳极，利用Co3O4在近红外光照射下的光热效应原位提高光阳极的温度，增强光生空穴迁移率的同时，促进表面的水氧化动力学，实现了BiVO4光阳极高效的光电化学水分解效率。主要制备得到了在光热辅助下具有高效光电化学性能的NiOOH/FeOOH/Co3O4/BiVO4光阳极：在近红外光照下，其在1.23 VRHE处的光电流密度达到6.34 mA cm-2，接近BiVO4基光阳极的理论光电流密度（7.50 mA cm-2）以及在0.6VRHE处2.72%的光电转换效率。重点通过多维度测试表征、结合理论计算厘清了光热增强光电化学水分解效率的内在机制，建立了光热转换与小极子跃迁之间的内在联系。为光阳极光电化学性能的提升找到了一种普适性的方法。本项目的实施，对于遵循小极子跃迁机制的过渡金属氧化物光阳极的光电化学水分解性能的优化具有重要的意义。