Highly Stable Layered Coordination Polymer Electrocatalyst toward Efficient CO2 -to-CH4 Conversion

Abstract

Cu²⁺ -based materials, a class of promising catalysts for the electrocatalytic carbon dioxide reduction reaction (CO₂ RR) to value-added chemicals, usually undergo inevitable and uncontrollable reorganization processes during the reaction, resulting in catalyst deactivation or the new active sites formation and bringing great challenges to exploring their structure-performance relationships. Herein, a facile strategy is reported for constructing Cu²⁺ and 3, 4-ethylenedioxythiophene (EDOT) coordination to stabilize Cu²⁺ ions to prepare a novel layered coordination polymer (CuPEDOT). CuPEDOT enables selective reduction of CO₂ to CH₄ with 62.7% Faradaic efficiency at the current density of 354 mA cm^-2 in a flow cell, and the catalyst is stable for at least 15 h. In situ spectroscopic characterization and theoretical calculations reveal that CuPEDOT catalyst can maintain the Cu²⁺ -EDOT coordination structurally stable in CO₂ RR and significantly promote the further hydrogenation of *CO intermediates, favoring the formation of CH₄ instead of dimerization to C₂ products. The strong coordination between EDOT and Cu²⁺ prevents the reduction of Cu²⁺ ions during CO₂ RR. The finding of this work provides a new perspective on designing molecularly stable, highly active catalysts for CO₂ RR.

Keywords: carbon dioxide reduction; flow cell; layered coordination polymer; methane; stability.