基于二维纳米异质结光催化陷阱的构建及催化增强机制研究

Aiming at the inefficient utilization of visible light and the low quantum efficiency during photocatalytic reduction CO2 over graphene-like carbon nitride, a new research idea is provided for greatly improving the visible light utilization and quantum efficiency of g-C3N4 by enhancing the light absorption, light excitation, and carriers separation and migration process synchronously in a light-trapping nanostructures, including two-dimensional nanosheet heterojunction, nanometal particles and light scattering layers. The purpose of this study is to explore effective synthesis methods and regulate the microstructures of two-dimensional nanosheet heterojunction MoS2/g-C3N4, Au, Ag nanoparticles and TiO2 light scattering layers. The effort will be devote to obtain the regulation approaches for the morphology, composition, interfacial and optical properties of the composite photocatalysis system. Meanwhile, the photoelectric coupling mechanism between MoS2/g-C3N4, Au, Ag nanoparticles and TiO2 light scattering layers will be clarified with the assistance of fluorescence spectra and theoretical calculation. In order to obtain the photocatalytic enhancement mechanism and achieve efficient reduction of CO2, the key factors which influence the light energy utilization efficiency in the light-trapping nanostructures will be obtained by revealing the relations between microstructures and catalytic performance. The result of this research will be of great significance for the development of photocatalysis technique and establishment of new energy system based on solar energy.

针对石墨相氮化碳（g-C3N4）光催化还原CO2反应过程中可见光利用率低和量子效率低的问题，提出将二维g-C3N4纳米片与层状金属硫化物MoS2复合构建二维纳米异质结光催化剂，并引入纳米金属表面等离子体效应和光散射效应共同构筑光催化陷阱，通过光吸收、光激发、载流子分离与迁移过程的同步强化，实现大幅提升g-C3N4可见光利用率和光量子效率的全新研究思路。旨在调控二维异质结2D-MoS2/g-C3N4、纳米金属Au、Ag和光散射层TiO2的微观结构，重点探索复合体系形貌、组成、界面及光学特性调控途径。借助荧光光谱和理论计算等途径，阐明二维纳米异质结-纳米金属-光散射层之间的光电耦合机制，揭示体系微观结构与催化性能之间的内在联系，获得光陷阱中影响光能高效耦合利用的关键因素，厘清反应增强机制，实现CO2高效还原。课题研究结果对光催化技术发展及建立以太阳能为核心的新能源体系具有重要科学价值。

为提升g-C3N4的光催化反应效率，项目以g-C3N4基半导体-半导体、半导体-金属异质结构建为基础开展研究，获得了一系列具有光能有效捕获-电荷高效分离-表面快速反应的光催化体系。通过对材料微观形貌、晶型结构、制备过程、光电特性、催化机制等开展研究，揭示了其活性-结构关系，重要研究结果如下：①以碱性溶剂热-阳极氧化法，获得了TiO2光散射基底，将其与g-C3N4、碳量子点薄膜、CdSe、ZnSe、Au、CdSe@ZnSe、Co2P等原位复合构建了具有高效光捕获性能的光陷阱，并揭示了上述体系的光催化增强机制；②借助高温煅烧、超声剥离等途径制备得到g-C3N4，并利用2D SnS2、2D FeSe2、RP、Co2P、Ni2P、NiCoP、CuCo2O4、ZnCo2O4材料与其复合构建II型、Z-Scheme等异质结，获得了上述不同异质结体系的催化增强机制；③构建了Bi2S3/g-C3N4、Sb2MoO6/g-C3N4、MoS2/CdIn2S4 S-Scheme异质结，研究表明S-Scheme电荷转移机制具有一定普适性，可很好解释实验现象；④针对窄带隙半导体红磷，探索得到了在其表面原位负载纳米金属（Au、Ag、Cu）及过渡金属（Co、Ni）磷化物的方法，已获授权发明专利2件；⑤为获得实用型光催化制氢体系，围绕硫化锌镉固溶体形貌调控等开展了部分工作，使其产氢速率达到了306.1mmol∙h-1∙g-1，在365nm单色光下表观量子效率达到了45.3%，实现了高效光解水制氢。项目在材料制备、机理研究等方面的实验和理论积累对光催化领域的相关研究具有借鉴意义。同时，项目直接或间接培养博士毕业生2名，硕士毕业生10名，先后发表SCI论文32篇，中文核心论文1篇，获中国授权发明专利4件，有效支撑了人才培养。