g-C3N4/Au-SnO2纳米簇复合材料的构建及可见光下光电协同催化还原CO2性能研究

Photocatalytic reduction of CO2 can utilize sunlight directly but enduring with low efficiency for the separation of photo-induced carriers. Electrocatalytic reduction can be properly controlled but with high energy consumption. Synergistic photoelectrocatalysis can give full play to the advantages of both, on the one hand drawing support from the photocatalytic activity to reduce energy consumption, on the other hand taking advantage of electrocatalytic effect to improve the reaction controllability. However, efficient and stable composites for synergistic photoelectrocatalytic reduction of CO2 under visible light are so scarce. This project intends to adopt graphitic carbon nitride (g-C3N4) as matrix to load ultrafine Au-SnO2 nanoclusters by light-induced reduction, and construct a novel composite material for synergistic photoelectrocatalytic reduction of CO2. In this composite material, g-C3N4 component performs as a visible light harvester and a skeleton to stabilize nanoclusters. The Au component in nanoclusters can promote the directional migration and separation of photo-induced carriers and provide the highly active catalytic sites. The SnO2 component can regulate the electrical activity and maintain nanoclusters’ highly dispersion and stability. All the factors above will greatly increase the efficiency of synergistic photoelectrocatalysis. Furthermore, we will investigate how the type of g-C3N4, the composition and structure of Au-SnO2 nanocluster influence the adsorption capacity and photoelectrocatalytic activity. A thorough understanding of the mechanisms of synergistic photoelectrocatalysis in the composite catalyst will provide new strategies and scientific basis for the design of multifunctional photoelectrcatalyst and the utilization of CO2 as a resource.

光催化还原CO2能直接利用太阳光但光生载流子分离效率较低，电催化还原可控性好但能耗较高，光电协同催化一方面借助光催化活性降低能耗，另一方面利用电催化作用提高反应可控性，能充分发挥二者的优势，但目前可见光下高效还原CO2的光电协同催化材料十分缺乏。本项目拟以石墨相氮化碳(g-C3N4)为基质，采用光诱导还原法负载小尺寸Au-SnO2纳米簇，构建新型光电协同催化还原CO2复合材料。该复合材料中g-C3N4可作为可见光捕获基质和纳米簇的稳定骨架，负载的纳米簇中Au能促进光生载流子的定向迁移并提供高活性催化位点，SnO2可调节电催化活性并保持纳米簇的分散稳定性，从而大幅度提高其光电协同催化效率。进一步探讨g-C3N4类型、纳米簇组成和结构对复合材料的吸附能力和光电催化活性等性能的影响，揭示此类复合材料的光电协同催化作用机制，为高效光电催化材料的设计和CO2的资源化利用提供新的策略和科学依据。

光电催化还原二氧化碳对温室气体有效控制和太阳能利用具有重要的科学意义和应用价值，构建新型高效、稳定的可见光光电协同催化材料是该领域中的重要课题。本项目研究围绕氮化碳和Au-SnO2纳米簇等材料，构建了系列光电催化的新型复合材料，成功设计制备了Au-SnO2与SnO2小尺寸纳米簇材料、石墨相和介孔氮化碳纳米材料、石墨烯负载金属卟啉的纳米复合材料等催化剂体系，系统表征了其光谱特性、光催化、光电催化活性，研究了制备条件对此类催化剂结构以及催化活性的影响，获得了相关材料调控的规律性认识。研究表明：调控柠檬酸亚锡等原料和紫外光诱导条件能有效控制小尺寸SnO2纳米簇的生成，匹配氮化碳与石墨烯等二维纳米材料的表面电荷对可见光光催化活性有重要影响，构筑和控制催化剂表面二氧化碳的浓度富集位点可有效提高光电催化活性。在项目资助下已发表SCI收录研究论文成果12篇（均已标注），其中影响因子大于4.0的6篇；申请发明专利4项，其中已授权2项；培养硕士研究生4名; 全面完成了项目的预期研究工作。