Molecular Engineering of Methylated Sulfone-Based Covalent Organic Frameworks for Back-Reaction Inhibited Photocatalytic Overall Water Splitting

作     者：Xiang Zhang Zhiwei Xiao Lei Jiao Huyue Wu Yan-Xi Tan Jing Lin Daqiang Yuan Yaobing Wang 

作者机构：CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou 350002 Fujian P. R. China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108 Fujian P. R. China University of Chinese Academy of Sciences Beijing 100049 P. R. China College of Chemistry and Materials Science Fujian Normal University Fuzhou 350007 P. R. China 

出 版 物：《Angewandte Chemie》 

年 卷 期：2024年第136卷第37期

学科分类：081704[工学-应用化学] 08[工学] 0817[工学-化学工程与技术] 

摘      要：Solar-to-hydrogen (H 2 ) and oxygen (O 2 ) conversion via photocatalytic overall water splitting (OWS) holds great promise for a sustainable fuel economy, but has been challenged by the backward O 2 reduction reaction (ORR) with favored proton-coupled electron transfer (PCET) dynamics. Here, we report that molecular engineering by methylation inhibits the backward ORR of molecular photocatalysts and enables efficient OWS process. As demonstrated by a benchmark sulfone-based covalent organic framework (COF) photocatalyst, the precise methylation of its O 2 adsorption sites effectively blocks electron transfer and increases the barrier for hydrogen intermediate desorption that cooperatively obstructs the PCET process of ORR. Methylation also repels electrons to the neighboring photocatalytic sulfone group that promotes the forward H 2 evolution. The resultant DS-COF achieves an impressive inhibition of about 70 % of the backward reaction and a three-fold enhancement of the OWS performance with a H 2 evolution rate of 124.7 μmol h −1 g −1 , ranking among the highest reported for organic-based photocatalysts. This work provides insights for engineering photocatalysts at the molecular level for efficient solar-to-fuel conversion.