3D多孔g-C3N4/贵金属复合光催化剂的构筑及其光解水性能研究

The collaborative optimization of noble metal and semiconductor is an important method to construct efficient water splitting photocatalyst. By way of a combination of theoretical calculations and practical experiments, the project selected 3D porous g-C3N4 and noble metals composite materials as the research target. Through designing porous metal/ceramic substrate and controlling the thermal polycondensation process of the precursor, achieve the controllable preparation of the covalent bond to the 3D porous g-C3N4. Through the crystal growth nucleation theory, we will achieve the fine regulation of the nanostructures of the noble metal co-catalyst. Optimize the noble metal deposition technology, building an effective interface, to achieve the overall synergy, and improve the efficiency of photocatalytic water splitting. The project will ascertain the relation between g-C3N4 porous structure, banding connection, energy band structure and optical absorption, electron transport, the mass transfer and charge utilization. To explore the association between morphology, component&composition, valence state of noble metal and the photocatalytic performance; Through the study of the binding mode and orientation relationship of noble metal and 3D g-C3N4, illustrate the effect on the separation of photoinduced charge as well as the transmission mode and direction thereof after the separation. Verify the association of water splitting efficiency with each unit optimization & multi-structure synergy, to maximize the photocatalytic activity. This project aims at providing theoretical support and new ideas for designing conductor/noble metal composites. Consider the synergetic effect of multi-structure as the core to construct the effecient water splitting photocatalysts.

半导体和贵金属的协同优化是构筑高效光解水催化剂的重要手段。本项目拟以3D多孔g-C3N4和贵金属为研究对象，采用实验和理论结合的研究方法，通过设计多孔金属/陶瓷衬底并调控热缩聚过程，实现共价键连接3D多孔g-C3N4的可控制备；结合晶体生长理论，实现多元贵金属助催化剂纳米结构的精细调控；优化贵金属负载技术，构筑有效界面，协同提高光解水效率。本项目将探明g-C3N4三维多孔结构、键连接方式、能带结构与光吸收、电子传输、传质、电荷利用之间的构效关系；探究贵金属的形貌、组分/组成、价态对助催化性能的影响；揭示贵金属与多孔 g-C3N4之间的界面结合方式、位向关系等对光生载流子分离及电子传输路径的影响；探明各组元优化、复合结构协同与光解水效率之间的构效关系，最大限度提高光催化活性。本项目研究旨在以多元结构协同优化为思想设计高效光催化剂，为半导体/贵金属高效光解水催化剂的设计提供理论支撑和新思路。

提高半导体/贵金属复合光催化剂光催化性能，需兼顾组分的多结构化和多功能化，整体设计、综合优化，同时提高光吸收效率、载流子分离效率和电荷利用效率。本项目以多孔g-C3N4和贵金属为主要研究对象，并扩展到其他材料体系，采用实验和理论结合的方法，揭示了半导体和贵金属协同优化与光解水效率之间的构效关系。通过分段调控富氮前驱体热缩聚过程，结合多孔硬模板优化，实现了3D多孔g-C3N4纳米结构及多孔g-C3N4微米管的可控制备及其表面修饰，阐明了多孔结构与光吸收和光生载流子传输之间的内在联系；通过控制无机盐熔融-分解和双氰胺的缩合-聚合过程，实现了Ag+单原子与Ag0团簇在g-C3N4层内及层间的分布，克服了其导电性能差的局限；进一步光还原沉积Au纳米颗粒，构筑了Au/Ag:CN复合光催化剂，利用多元贵金属的等离子体共振效应和光吸收、光生载流子分离与催化活性之间的协同机制提高了可见光催化裂解水产H2性能，揭示了贵金属的形貌、组分/组成、价态对催化性能的影响；基于杂原子掺杂，实现了g-C3N4电子能级的连续调节，构筑了CN-M/CN-U/Pt-TiO2三元异质结和PCN/ACN Z型结，探究了其光催化裂解水产H2性能，阐明了复合材料中界面电势对光生电荷传输的影响机制；在本项目研究基础之上，围绕复合材料界面结构调控和界面载流子传输路径优化，拓展研究并构筑了系列复合光电催化剂体系，采用密度泛函理论计算方法，揭示了贵金属-半导体之间的相互作用方式、表界面电子调控机制以及表界面缺陷调控等对裂解水产H2、CO2还原等催化反应的影响机制。本研究的成果有助于揭示多元结构协同优化与光催化性能的关系，可为设计实用、高效和长寿命的光催化剂提供一种新思路。在研究成果方面，发表英文论文11篇，培养硕士、博士研究生10名。在项目的执行过程中，项目负责人负责组织了中国化学会第十届全国无机化学学术会议“无机催化材料分会”（2019.08.18-2019.08.21，山东大学），促进了学术交流。