Simultaneous High Current Density and Selective Electrocatalytic CO2-to-CH4 through Intermediate Balancing

Abstract

The electrochemical reduction of CO₂ to CH₄ is promising for carbon neutrality and renewable energy storage but confronts low CH₄ selectivity, especially at high current densities. The key challenge lies in promoting *CO intermediate and *H coupling while minimizing side reactions including C−C coupling and H−H coupling, which is particularly difficult at high current density due to abundant intermediates. Here we report a cooperative strategy to address this challenge using Cu-based catalysts comprising Cu−N coordination polymer and CuO component that can simultaneously manage the key intermediates *CO and *H. A fast CO₂-to-CH₄ conversion rate of 3.14 mmol cm⁻² h⁻¹ is achieved at 1,300 mA cm⁻² with a Faradaic efficiency of 51.7 %. In situ spectroscopy and theoretical calculations show that the increased Cu−Cu distance in the Cu−N coordination polymer component favors multistep *CO hydrogenation over the dimerization, and the CuO component ensures an adequate supply of *H, together contributing to the selective CO₂-to-CH₄ conversion at high current densities. This work develops a cooperative strategy for the electrosynthesis of CH₄ with simultaneous high current density and high selectivity by rational catalyst design, paving the way for its applications.