Cao Heng, Jiang Shenlong, Xue Jiawei, Zhu Xiaodi, Zhang Qun, Bao Jun
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
Hefei National Research Center for Physical Sciences at the Microscale, Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
J Phys Chem Lett. 2022 Sep 15;13(36):8397-8402. doi: 10.1021/acs.jpclett.2c01983. Epub 2022 Sep 1.
The photocatalytic CO reduction to CH reaction is a long process of proton-coupled charge transfer accompanied by various reaction intermediates. Achieving high CH selectivity with satisfactory conversion efficiency therefore remains rather challenging. Herein, we propose a novel strategy of unpaired electron engineering to break through such a demanding bottleneck. By taking TiO as a photocatalyst prototype, we prove that unpaired electrons stabilize the key intermediate of CH production, i.e., CHO*, via chemical bonding, which converts the endothermic step of CHO* formation to an exothermic process, thereby altering the reaction pathway to selectively produce CH. Meanwhile, these unpaired electrons generate midgap states to restrict charge recombination by trapping free electrons. As an outcome, such an unpaired electron-engineered TiO achieves an electron-consumption rate as high as 28.3 μmol·g·h (15.7-fold with respect to normal TiO) with a 97% CH selectivity. This work demonstrates that electron regulation holds great promise in attaining efficient and selective heterogeneous photocatalytic conversion.
光催化将CO还原为CH的反应是一个伴随着各种反应中间体的质子耦合电荷转移的漫长过程。因此，要实现具有令人满意的转化效率的高CH选择性仍然颇具挑战性。在此，我们提出一种新颖的不成对电子工程策略来突破这一苛刻的瓶颈。以TiO作为光催化剂原型，我们证明不成对电子通过化学键合稳定CH生成的关键中间体即CHO*，这将CHO*形成的吸热步骤转变为放热过程，从而改变反应途径以选择性地生成CH。同时，这些不成对电子产生带隙中间态，通过捕获自由电子来限制电荷复合。结果，这种经过不成对电子工程处理的TiO实现了高达28.3 μmol·g·h的电子消耗速率（相对于普通TiO提高了15.7倍），CH选择性达97%。这项工作表明，电子调控在实现高效且选择性的多相光催化转化方面具有巨大潜力。
