Cu等离子体共振增强光电催化性能的双重构效关系耦合调控

The optical property and the charge carrier transport ability of semiconducting photoelectrocatalytic materials are the main limitations for the improved photoelectrocatalytic activity for solar hydrogen generation. Metal plasmon resonance could effectively improve the optical property and the charge transport ability of semiconductors; however, most of the studies have been focused on noble metals like Au and Ag, because it is hard to synthesize stable and pure Cu nanostructures. This project will focus on the fabrication of low cost, stable, and structure and composition controlled Cu nanostructures, to couple with nanostructured semiconductors (previous results), to design plasmonic photoelectrocatalysts with enhanced activities. We will first synthesize stable Cu nanostructures by alloying (i.e., composition and structure) and coating insulator overlayer (i.e., interface structure); then, the plasmon resonance effect will be optimized by synergistically engineering the dual structure-function relationships of “composition and structure-plasmon resonance” and “interface structure-plasmon resonance” for efficient optical absorption and charge separation and then enhanced photoelectrocatalytic activities for solar hydrogen generation. This project will experimentally and theoretically investigate the charge excitation and transport, and photoelectrocatalytic reaction mechanisms as affected by plasmon resonance, and reveal the fundamentals of dual structure-function relationship engineering, providing theoretical principles for designing high efficiency plasmonic photoelectrocatalysts.

半导体光电催化材料的光响应性能和载流子迁移能力是光电催化分解水制氢性能的主要限制因素。金属等离子体共振效应可有效增强半导体的光响应和载流子迁移能力；然而，由于稳定的单质纳米Cu难以制备，研究多集中于Au和Ag等贵金属。本项目拟制备低成本、稳定的、结构组成可调控的Cu纳米结构，并耦合微纳结构半导体（前期研究基础），构建等离子体共振增强型光电催化材料。首先，通过合金化（即组成结构）和构筑表面绝缘层（即界面结构）获得稳定的Cu等离子体；接着，以“组成结构-等离子体共振”和“界面结构-等离子体共振”双重构效关系的耦合调控，优化等离子体共振效应，实现Cu等离子体光电催化材料的高效光响应和载流子强化分离，增强其光电催化性能。本项目将从实验和理论角度对等离子体共振效应作用下的载流子激发迁移机制、光电催化反应机理进行深入研究，揭示双重构效关系耦合调控机制，为高效等离子体光电催化材料的设计提供理论指导。

为实现光电催化过程中高效光子吸收以及高效光生载流子分离与迁移，本项目重点研究Cu等离子体共振增强型光电催化材料，通过Cu等离子体组成结构与表面绝缘层的调控与构筑，实现等离子体共振对光电催化材料光响应特性与载流子传输特性的协同优化，有效增强光电催化性能。首先，本项目利用水溶液还原法制备了不同尺寸、不同组成和不同形貌的Cu等离子体，掌握了纳米Cu等离子体的可控制备经验与规律，揭示了Cu等离子体光电催化材料组成结构与界面结构对等离子体共振效应以至光电催化性能的影响规律。其次，基于Cu等离子体，通过耦合半导体或绝缘体外壳，制备了Cu@C、Cu@SiO2和Cu@TiO2等一系列核壳结构光电催化材料，实现了高效的光催化分解纯水制氢，性能位于同类材料的同期报道最高水平。进而，基于Cu等离子体光电催化材料的制备经验，将该方法延用至不同尺寸、不同形貌的Au等离子体的可控制备；并进一步发展了基于Au和Ag等离子体的高效光电催化材料。最后，利用表面光电压谱、荧光光谱和同步辐射等先进表征技术并结合FDTD等理论模拟方法，深入研究了CuNi@C3N4、Cu@TiO2、Cu@C、Cu@C@TiO2和Fe2O3/Au/TiO2等等离子光电催化材料的组成结构、界面结构和空间结构对等离子体共振效应、界面载流子迁移规律、光电极/电解质界面的电荷传递及表面水氧化反应机理，为等离子体光电催化材料的理性设计提供了理论与实验指导。在Advanced Materials、Science Bulletin等国内外重要期刊发表SCI论文40篇，国内外重要会议作邀请报告20余次，申请和授权国家发明专利各1项，毕业硕士4名、博士2名，出站博士后1名。