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.