Effect of Electronic Structure over Late Transition-Metal M<sub>1</sub>–N<sub>4</sub> Single-Atom Sites on Hydroxyl Radical-Induced Oxidations
Jianglin Duan, Yanan Zhou, Yujing Ren, Fenli Liu, Pengcheng Deng, Man Yang, Huibin Ge, Jie Gao, Jinlong Yang, Yong Qin
Abstract
Hydroxyl radical ( • OH)-induced oxidations are of great importance in chemical transformations. Carbon-supported late transition-metal single-atom catalysts (SACs) with bioinspired M 1 –N 4 single-atom sites can effectively activate the peroxide group to produce • OH. Nevertheless, little is known about how electronic structures of M 1 –N 4 sites affect • OH generation. Herein, dependent on the theoretical design and experimental realization of uniform M 1 –N 4 /C (M: Fe, Co, Ni, and Cu) SACs, a positive correlation relationship between • OH-induced oxidation activity and d-band center over the M 1 –N 4 site has been revealed. In detail, by changing the M atoms with different numbers of d electrons, the d-band center of the M 1 –N 4 could be turned. Moreover, the enhancement of d-band center heightens the interaction strength between the • OH intermediate and the M 1 –N 4 site, which results in a higher oxidation activity. In this case, the efficient M 1 –N 4 catalyst for the oxidation reaction can be screened by tuning the doped M atom. Moreover, notably, Fe 1 –N 4 with the highest d-band center value has the lowest free energy change of the rate-determining step (0.06 eV) for • OH generation. Taking advantage of this, in both Fenton-like reaction and • OH-induced C–H bond activation reaction, the Fe 1 –N 4 site displays at least 1 order of magnitude higher activity than the most of the supported late transition-metal catalysts and comparable activity to reported noble metal catalysts. This work is expected to provide guidance for designing high-efficiency heterogeneous catalysts in • OH-induced oxidations and bridge heterogeneous and enzymatic catalysis by using M 1 /C SAC as a platform.