基于氧空位调控的磷酸铋/亚纳米铜复合光催化剂对水中硝酸盐的光催化还原增效机制研究

开发有效的硝酸盐脱除技术对我国地表水污染防治具有重要意义。将光催化还原技术用于硝酸盐去除已受到广泛关注，但催化剂效率的进一步提高和对外源空穴捕获剂的依赖性是该技术发展面临的主要问题。本研究拟利用光催化法调控磷酸铋的氧空位以构建其与亚纳米级铜颗粒耦合的复合催化剂，用于水中硝酸盐的高效光催化还原脱除及还原产物的有效调控。首先依据密度泛函理论计算态密度和能级以优化复合催化剂的构建，系统表征材料的理化界面特性，并阐述材料构成组分及尺寸效应对其还原性能的耦合作用机制；随后识别影响硝酸盐光催化还原的主导环境因子，论证天然有机质作为内源空穴捕获剂的可行性并阐明其参与机制；进一步分析中间产物和特征自由基，阐述多环境因子共存与复合催化剂的构成组分对硝酸盐光催化还原的协同作用机理，并利用顺序速率检测法建立多环境因子共存下硝酸盐光催化还原的反应动力学方程，为地表水中硝酸盐的污染防治提供理论基础和技术支持。

An efficient approach for nitrate removal is important for the pollution control in surface water. Photocatalytic reduction of nitrate has been studied widely. However, its application has been limited by the relatively low efficiency of photocatalyst and the dependence on hole scavengers. To address these issues, a composite photocatalyst of oxygen vacancy mediated BiPO4 and Cu sub-nanoparticles will be fabricated. The composite will be evaluated by Density Functional Theory and characterized comprehensively, while the oxygen vacancies will be manipulated through a photocatalytic method. The effect of catalyst composition and size on the photocatalytic reduction rate and final product species will be studied. Key environmental factors that may affect the photocatalytic reduction of nitrate will also be identified. Moreover, the feasibility of natural organic matters as hole scavengers will be evaluated. By measuring the intermediates and final products from the photocatalytic reduction of nitrate, the roles of BiPO4, Cu, oxygen vacancy, and natural organic matters will be studied. A kinetic model of this process will be given based on a method named Sequential Rate Technique. It is hoped that this study can provide insights for nitrate pollution control, especially for the development of photocatalytic reduction of nitrate.