N掺杂石墨烯&准二维纳米结构MIn2S4复合光催化剂的构筑及光催化还原CO2性能

The increasingly serious energy crisis and the environmental contamination have stimulated intense research on solar energy utilization. The development of a novel solar photocatalytic reduction CO2 system to realize CO2 conversion and utilization has important scientific value and profound practical significance. Based on the thermodynamic principle, a novel solar photocatalytic reduction CO2 system was obtained by using an appropriate band gap energy quasi-two-dimensional MIn2S4 semiconductor coupled with nitrogen (N) doped graphene with considerable oxygen vacancies. Then, a series of high efficient photocatalytic reduction CO2 composite catalysts with multiple type heterojunctions are fabricated by precious metal deposition and sulfide coated modified. These catalysts have a good performance of CO2 adsorption, an enhanced absorbance in the visible-light region and high light quantum efficiency. First, the effect oxygen vacancy concentration on the surface of the catalyst on the CO2 adsorption ability is studied; Second, the band structure of the catalysts are discussed. The objective of the study is to provide a theoretical basis for thermodynamics to solve the possibility of photocatalytic reduction CO2. Last, the intrinsic relationship between photocatalyst structure, composition and the activity of reduction CO2, and the mechanism of nano-heterojunction to inhibit light-induced charge recombination is explored. The objective of the study is to improve the efficiency of photocatalytic reduction CO2.

开发高效太阳光催化还原CO2新体系，实现CO2的转化与利用，解决人类日益严峻的燃烧污染和能源紧缺问题，具有重要的科学价值和深远的现实意义。本项目基于热力学原理，优选与光催化还原CO2相匹配能带结构的准二维纳米结构MIn2S4半导体与通过氮(N)掺杂实现石墨烯表面大量氧缺位的石墨烯复合，构筑CO2吸附性能好、可见光响应范围宽和光量子效率高的太阳能光催化还原CO2新体系。并对复合体进行贵金属沉积和金属硫化物包覆等修饰，获得多种异质结协同作用的高效光催化还原CO2复合光催化剂。研究催化剂表面氧缺位浓度对CO2吸附性能影响，为提高催化剂吸附性能探索基本规律；研究复合催化剂能带结构与还原CO2电位匹配性，为热力学上解决可见光催化还原CO2的可能性提供理论依据；研究光催化剂的结构、组成与还原CO2活性的内在关系，探索多种异质结协同作用抑制光致电荷复合机理，提高光催化还原CO2量子效率。

能源危机和环境问题是21世纪人类面临的两个严峻挑战。开发高效太阳光催化新技术获得氢能以及还原CO2新体系，实现CO2的转化与利用，解决人类日益严峻的燃烧污染和能源紧缺问题，具有重要的科学价值和深远的现实意义。本项目主要完成以下研究内容:（1）采用N掺杂石墨烯（N-GE）复合MIn2S4半导体分别制备了N-GE/ZnIn2S4、N-GE/CdIn2S4两种复合光催化剂。光照5h内N-GE/ZnIn2S4¬复合光催化剂产氢量达到1949.8 μmol；光照10 h内该催化剂还原CO2生成甲酸甲酯 (MF) 产量达到7859.65 μmol。光照5h内N-GE/CdIn2S4复合光催化剂产氢量达到1649.6 μmol；光照10 h内该催化剂还原CO2生成甲酸甲酯 (MF) 产量达到7859.65 μmol。（2）采用N-GE复合WO3半导体制备了N-GE/WO3复合光催化剂。光照60 min后甲基橙脱色率接近100%。（3）采用Ag修饰N-GE复合TiO¬2半导体制备了Ag/N-GE/TiO2复合光催化剂。光照10 h内该催化剂产氢量达到1132.54 μmol。（4）以尿素与硫脲为原料，采用热分解法制备了g-C3N4/g-C3N4(M-CN)复合光催化剂。光照6h内，M-CN光催化产氢量速率达780.5μmol/g.h；采用高温氢化法分别制备了氢化g-C3N4/g-C3N4(HM-CN)、氢化g-C3N4(HT-CN)两种光催化剂。光照6h内，HM-CN光催化产氢量速率达1254.2μmol/g.h，HT-CN光催化产氢量速率达758.9μmol/g.h。本项目的研究工作为开发廉价、便捷的新型光催化技术，为解决人类目前面临的严重环境污染、能源危机提供了有效的技术支持。