Design of reaction-driven active configuration for enhanced CO2 electroreduction

Abstract

Metal-nitrogen-carbon single-atom catalysts (SACs) have emerged as promising candidates for electrocatalytic CO2 reduction reaction. However, the perpendicular dz2 orbital within planar metal site mainly interacts with *COOH, resulting in inferior CO2 activation. Inspired by reaction-driven active configuration, here we propose to upshift nickel single-atom away from nitrogen-carbon substrate, prominently promoting the interaction between CO2 and other d orbitals besides dz2 . Theoretical and experimental analyses reveal that upshifting nickel site away substrate induces dxz, dyz, and dz2 to hybridize with CO2, expediting CO2 conversion to *COOH. The planar and out-of-plane Ni-N sites are formed on carbon nanosheet (Ni1-N/CNS) and curved nanoparticle (Ni1-N/CNP), respectively, which is verified by X-ray absorption fine structure spectroscopy. Impressively, the Ni1-N/CNP presents CO Faradaic efficiency of 96.4 % at 500 mA cm− 2 and energy conversion efficiency of 79.8 % in flow cell, outperforming Ni1-N/CNS and most SACs. This work highlights the simulation of reaction-driven active sites for efficient electrocatalysis.