Tracking Mechanistic Pathway of Photocatalytic CO 2 Reaction at Ni Sites Using Operando, Time-Resolved Spectroscopy

作者：Yangguang Hu, Fei Zhan, Qian Wang, Yujian Sun, Can Yu, Xuan Zhao, Hao Wang, Ran Long, Guozhen Zhang, Chao Gao, Wenkai Zhang, Jun Jiang, Ye Tao, Yujie Xiong · 发表于：Journal of the American Chemical Society · 年份：2020 · DOI：10.1021/jacs.9b12443 · 被引用次数：188 · 研究领域：CO2 Reduction Techniques and Catalysts、Advanced Photocatalysis Techniques、Carbon dioxide utilization in catalysis

Harvesting solar energy for catalytic conversion of CO 2 into valuable chemical fuels/feedstocks is an attractive yet challenging strategy to realize a sustainable carbon-cycle utilization. Homogeneous catalysts typically exhibit higher activity and selectivity as compared with heterogeneous counterparts, benefiting from their atomically dispersed catalytic sites and versatile coordination structures. However, it is still a “black box” how the coordination and electronic structures of catalysts dynamically evolve during the reaction, forming the bottleneck for understanding their reaction pathways. Herein, we demonstrate to track the mechanistic pathway of photocatalytic CO 2 reduction using a terpyridine nickel(II) complex as a catalyst model. Integrated with a typical homogeneous photosensitizer, the catalytic system offers a high selectivity of 99% for CO 2 -to-CO conversion with turnover number and turnover frequency as high as 2.36 × 10 7 and 385.6 s –1, respectively. We employ operando and time-resolved X-ray absorption spectroscopy, in combination with other in situ spectroscopic techniques and theoretical computations, to track the intermediate species of Ni catalyst in the photocatalytic CO 2 reduction reaction for the first time. Taken together with the charge dynamics resolved by optical transient absorption spectroscopy, the investigation elucidates the full mechanistic reaction pathway including some key factors that have been often overlooked. This work opens th...