Self-healing Cu single-atom catalyst for high-performance electrocatalytic CO2 methanation

Abstract

To address the escalating challenge of atmospheric CO2 emissions, this study proposes a self-healing Cu single atom (SA) catalyst design. By partially cleaving Cu-N bonds via hydrogen evolution reaction (HER), coordinatively unsaturated Cu sites form and spontaneously bond with adjacent ZrO2 clusters which are strategically positioned near the Cu SA, creating a hybrid Cu-N/O structure with enhanced performance. In situ Raman and X-ray absorption fine structure (XAFS) measurements confirm the dynamic reconstruction of coordination environment from CuN4 to CuN1O2 under electrochemical conditions. The reconstructed CuN1O2 achieve observed performance for CO2-to-CH4 conversion, reaching a Faradaic efficiency of 87.06 ± 3.22% at −500 mA cm−2 and 80.21 ± 1.01% at −1000 mA cm−2, which are threefold and tenfold higher than those of pristine CuN4. Furthermore, a 25-h stability test with 500 mA cm−2 current density in a membrane electrode assembly (MEA) electrolyzer demonstrates minimal activity decay (< 3%). Density functional theory (DFT) calculations demonstrate that self-healing mechanisms optimize intermediate adsorption and electron distribution. This strategy enables efficient muti-electron transfer processes under industrial conditions, working to improve the stability of single-atom catalysts and develop scalable catalytic systems.