Academic News: Major Progress in COF Photocatalytic CO₂ Conversion Published by College of Chemistry and Materials Science in Advanced Materials

Recently, the research group led by Associate Professor Lan Xingwang from the College of Chemistry and Materials Science has made significant progress in the field of COF-based photocatalytic CO₂ conversion. The related work, titled “Spatial Cascade Sites in Hierarchical COF-Based Photocatalyst Enable C–C Coupling for Selective CO₂ Photoreduction to Ethylene,” has been published in the world-leading journal Advanced Materials (2026, e73201, IF = 26.8), with Hebei University as the first affiliated institution. Xu Haobo, a master’s student at the college, is the first author, Associate Professor Lan Xingwang is the corresponding author from the first affiliated institution, and Professor Chen Yong from the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, and Professor Edmund C. M. Tse from the University of Hong Kong are co-corresponding authors.

Against the backdrop of global warming and the depletion of fossil energy, converting the greenhouse gas CO₂ into high-value-added chemicals has become a major focus of scientific research. Among the various possibilities, the reduction of CO₂ into C₂⁺ products (e.g., ethylene), which contain two or more carbon atoms, has garnered particular attention due to their high energy density and broad industrial application prospects. However, this process faces key challenges, including slow multi-electron/proton transfer and high kinetic energy barriers for C–C coupling. Covalent organic frameworks (COFs) are a class of porous organic materials with well-defined crystalline structures, showing broad application potential in gas storage and separation, catalysis, and optoelectronics. Although COFs have attracted considerable interest for photocatalytic CO₂ reduction, their conversion efficiency remains low due to insufficient active sites and unsatisfactory charge separation, with reduction products primarily limited to C₁ species.

To address these challenges, the research team innovatively proposed a strategy for constructing hierarchical tandem photocatalysts. Specifically, they in-situ composited non-stoichiometric indium sulfide with an imine-pyridine COF and anchored isolated nickel single-atom sites at the interfacial edges of the COF, forming a core–shell heterojunction with spatially separated cascade active sites (denoted as IS@COF-Ni). Experimental results show that under visible light irradiation, using water vapor as the reductant without any noble metals or sacrificial agents, this catalyst achieves an ethylene production rate of 49.2 µmol·g⁻¹·h⁻¹ with a selectivity as high as 86.3%. In contrast, pure COF or indium sulfide components produce only CO, highlighting the critical role of spatially cooperative sites in facilitating C–C coupling. Through in-situ spectroscopic characterization and theoretical calculations, the study further elucidates the microscopic mechanism for efficient ethylene generation over IS@COF-Ni, proposing a tandem catalytic mechanism in which CO species adsorbed on the heterojunction surface undergo direct dimerization at spatially adjacent active sites to form the key *COCO intermediate. This work presents an innovative mechanism involving the synergistic regulation of multi-electron reactions and C–C bond formation through spatial cascade sites and interface engineering, offering new insights for designing photocatalysts for CO₂ reduction to multi-carbon products.

This work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Hebei Province, and the Young Top-Notch Talent Program of the Institute of Life Sciences and Green Development, Hebei University.

Article link:https://doi.org/10.1002/adma.2024073201