"Capture-activation-recapture" mechanism-guided design of double-atom catalysts for electrocatalytic nitrogen reduction

Compared with the traditional industrial nitrogen fixation, electrocatalytic methods, especially those utilizing double-atom catalysts containing nonmetals, can give good consideration to the economy and environmental protection. However, the existing "acceptance-donation" mechanism is only applicable to bimetallic catalysts and nonmetallic double-atom catalysts containing boron atoms. Herein, a novel "capture-activation-recapture" mechanism for metal-nonmetal double-atom catalyst is proposed to solve the problem by adjusting the coordination environments of nonmetallic atoms and utilizing the activation effect of metal atoms on nitrogen. Based on this mechanism, the nitrogen reduction reaction (NRR) activity of 48 structures is calculated by density functional theory calculation, and four candidates are selected as outstanding electrocatalytic nitrogen reduction catalysts: Si-Fe@NG (U-L = -0.14 V), Si-Co@NG (U-L = -0.15 V), Si-Mo@BP1 (U-L = 0 V), and Si-Re@BP1 (U-L = -0.02 V). The analyses of electronic properties further confirm "capture-activation-recapture" mechanism and suggest that the difference in valence electron distribution between metal and Si atoms triggers the activation of N N bonds. In addition, a machine learning approach is utilized to generate an expression and an intrinsic descriptor that considers the coordination environment to predict the limiting potential. This study offers profound insight into the synergistic mechanism of TM and Si for NRR and guidance in the design of novel doubleatom nitrogen fixation catalysts. (c) 2024 Published by ELSEVIER B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.