P-CuBi2O4处理含Cr(Ⅵ)废水光阴极的光电化学性能研究

Cr(VI) is carcinogenic with high mobility in water, and developing a cost-effective and environmentally friendly method for treating Cr(VI)-containing wastewater is an important challenge for the metallurgical industry. In this project, photoelectrochemical reduction of Cr(VI) by in-situ self-assembled p-CuBi2O4 was proposed to meet the above challenges. The effect of preparation process on the composition, structure and morphology of CuBi2O4 was revealed, and that of its optical, electrical and photoelectrochemical properties were described. Combining various spectral characterization and photoelectrochemical analysis methods, the limiting step and the change of surface chemical composition and crystal structure of CuBi2O4 in the process of photoelectrocatalytic reduction of Cr(VI) were investigated. The key factors which limiting the photoelectrochemical efficiency and stability of CuBi2O4 were analyzed. According to the key factors, the CuBi2O4 photoelectrode was doped, surface modified or synergistically modified, and its impact on photoelectrochemical performance and stability was studied. The design basis was summarized to develop highly efficient and stable CuBi2O4 photocathode for photoelectrocatalytic reduction of Cr(VI). The results of this project would have important theoretical and practical guidance for the development of new photoelectrochemical electrode materials, solving the current water pollution problems, and opening up new ways of environmental governance.

Cr(VI)具有致癌性和高流动性，发展经济有效且环保的方法处理含Cr(VI)废水是冶金行业所面临的重要挑战。本项目提出以原位自组装的p-CuBi2O4进行光电催化还原Cr(VI)来应对上述挑战，揭示制备工艺对CuBi2O4成分、结构以及形貌的调控方法，阐述其对光学、电学以及光电化学性能的影响机制。结合多种光谱表征和光电化学分析手段，探究CuBi2O4光电催化还原Cr(VI)过程中的限制性步骤和表面化学组分和晶体结构的改变，分析制约CuBi2O4光电催化效率和稳定性的关键性因素。依据关键性因素对CuBi2O4光电极进行掺杂、表面修饰或两者协同作用，研究其对光电性能和稳定性的作用原理，总结设计依据，开发光电催化还原Cr(Ⅵ)用高效稳定的CuBi2O4光阴极。项目成果对于开发新型光电催化电极材料，解决当前水体污染治理问题，开辟环境治理的新途径具有十分重要的理论与实际指导意义。

Cr(VI)作为冶金工业废水中常见的污染物，具有致癌性和高流动性，传统方法成本高且易造成二次污染，因此，发展经济有效且环保的方法处理含Cr(VI)废水是冶金行业所面临的重要挑战。本项目提出以原位自组装的p-CuBi2O4进行光电催化还原Cr(VI)来应对上述挑战，研究不同电化学沉积工艺、化学水浴沉积工艺以及退火工艺对CuBi2O4薄膜组成、结构和形貌的影响，同时系统表征CuBi2O4薄膜的光学性质、电学性质和光电化学性质，获得质量稳定可控的CuBi2O4薄膜原位自组装工艺。构建光电化学池，研究CuBi2O4薄膜在光电催化还原Cr(VI)过程中的限制性步骤和表面化学组分以及晶体结构的改变，分析导致CuBi2O4薄膜电极光电效率低以及稳定性差的关键因素，并在此基础上发展适合光电催化还原Cr(VI)用CuBi2O4薄膜的高效光电化学评价体系。经过工艺优化后的电沉积法制备的Cu2O纳米薄膜表面均匀形貌可控，在此基础上制备的CuBi2O4纳米薄膜通过工艺优化界面修饰等，具有良好的结晶性，是与基底接触良好、无断层且由尺寸均一的晶粒连续堆积而成的薄膜。改性后的CuBi2O4纳米薄膜的光电流密度明显大于传统的CuBi2O4光电极且在455 nm LED（39 mW·cm-2）光源下可以达到-2.47 mA·cm-2@0.6 VRHE的光电流密度值，具有优异的光电性能。另外，改性后的CuBi2O4光阴极比传统的CuBi2O4光阴极的内量子效率高很多，其最大值为22.1%，比传统CuBi2O4光电极增大10倍。这说明通过工艺优化和界面改性的协同作用缩短了光激发产生的电子从体相迁移到表面的距离，减少了电子与空穴复合的可能性，从而有效地提高了其量子效率。对CuBi2O4纳米薄膜进行光电催化还原Cr(VI)测试，结果显示在合适测试条件下，CuBi2O4纳米薄膜具备了光电催化还原Cr(VI)的能力，且具有一定的稳定性。本项目所得到的这些重要结果和关键数据对于开发新型光电催化还原Cr(Ⅵ)用高效稳定的光电极材料，解决当前水体污染治理问题，开辟环境治理的新途径具有十分重要的理论与实际指导意义。