液固界面下CO2/H2O光催化转化机制研究和活性理性调控

Photo-electrocatalytic conversion of CO2 together with H2O oxidation is one of the most effective and profound strategies to realize its resource utilization that solves the greenhouse effect and energy crisis simultaneously. However, this system has long been encountering the problems of low catalytic efficiency owing to the high overpotential. In view of these key issues, this project would, by combining the density functional theory calculation and microkinetic analysis method, focus on the following targets: (i) exploring the excitation and localization/transport behavior of the photogenerated electron and hole at the surface or interface of some important photocatalyst materials, and resolving the correlation between the local structure of catalyst material and the trapping ability toward the photogenerated electron and hole; (ii) giving an atomic level understanding toward the reaction mechanism of CO2 photo-electrocatalytic reduction and H2O oxidation into O2 catalyzed by the single-crystal, amorphous-crystal and composite materials, respectively, in which one of the main aims is to identify the crucial roles of the photogenerated electron and hole; also, we are aiming at establishing a quantitative activity estimation model based on the complete microkinetic framework containing all the related elementary steps, and digging out the rate-determining step or some rate-limiting physical properties; (iii) testing the effect of the surface configuration and constituent of catalyst on modulating the catalytic ability of the photogenerated electron and hole, and also on the general rule in activating the basic C-O, C-H and O-O bond, with the aim of showing a broad-range and inherent correlation of structure and the overall photocatalytic performance. This proposal would evidently enhance the recognization on logically characterizing the highly reactive active-site, and its accomplishment could eventually help improve the conversion efficiency of CO2 and rational design of new structure.

CO2光电催化还原是实现其资源化利用，缓解人类社会温室效应和能源问题最具深远意义的方法之一，但目前仍未解决催化效率低下的问题，这根本上需要增强光/电转化基本化学机制及规律认知和材料理性优化调控。以此为背景，本项目拟主要采用密度泛函理论结合微观动力学统计方法，重点研究：i）光生电子和空穴在表界面的激发局域和传输性质，解析光材料微观结构对光电子和空穴局域的影响机制和规律；ii) 在原子水平上探究液固界面下单晶、非晶和复合型结构材料催化CO2光还原基元反应及水分解产氧/产氢机制，揭示光生电荷在CO2和H2O分子吸附及转化中的关键角色，并建立完整的微观动力学活性评估模型，揭示关键的决速步骤或因素；iii) 探索催化剂微观结构、组成等在调控电子/空穴反应性能和活化C–O、C-H、O-O键能的共性规律，促进高效活性位结构的认知和预测。项目的实施有助于为实质性提高CO2利用效率和新结构设计提供理论依据。

项目围绕“液固界面下CO2/H2O光催化转化机制研究和活性理性调控”开展了系统的研究工作，主要包括：表界面载流子的局域及传输机制、复杂反应体系液固界面理论模拟方法发展及应用、光电催化技术的本质特征及在常见化学键活化方面的共性规律、催化材料与性能间的基础构效关系、催化反应动力学方法及程序发展等，立足于解决液固界面CO2/H2O光电催化转化领域所涉及的底层共性问题、焦点机制和难点问题。经过四年的开展实施，取得了以下四点代表性进展：（i）揭示了光生空穴对典型化学键（如C-O、C-H、O-H键等）活化的调控规律，剖析了光电催化的不同作用机制和关键催化角色，并证明了光电联用催化技术的可行性；（ii）解析了液固界面环境下典型催化材料催化CO2光电还原反应、H2O光电分解产氧/产氢反应机制、以及CH3OH光氧化转化等重要光电催化过程，揭示了光生电子和空穴在CO2和H2O分子吸附及转化过程中的关键角色；（iii）结合机器学习、基因算法等技术开展了较系统的构效关系挖掘，围绕CO2还原和OER/HER三大反应体系，探究了若干典型材料活性中心特性与催化性能之间的关联关系，促进新型催化剂高效活性位特征的认知和预测；（iv）围绕多相催化基础活性理论发展及催化剂寻优设计，项目从底层构筑了催化剂特征与催化反应本身热力学性质之间的关联关系，并建立三维火山型曲面的解析模型，深入揭示了催化材料“结构-描述符-活性”之间的关联关系；同时，面向复杂光电催化体系动力学解析，发展了一套功能完善的微观动力学程序。已发表标注项目编号的SCI学术论文32篇，包括 J. Am. Chem. Soc.、JACS Au、Angew. Chem. Int. Ed.、ACS Catal. 等影响因子>9论文15篇，培养博士研究生3名。总体较好地完成了项目目标。