Steering surface reconstruction of copper with electrolyte additives for CO₂ electroreduction

Electrocatalytic CO₂ reduction to value-added hydrocarbon products using metallic copper (Cu) catalysts is a potentially sustainable approach to facilitate carbon neutrality. However, Cu metal suffers from unavoidable and uncontrollable surface reconstruction during electrocatalysis, which can have either adverse or beneficial effects on its electrocatalytic performance. In a break from the current catalyst design path, we propose a strategy guiding the reconstruction process in a favorable direction to improve the performance. Typically, the controlled surface reconstruction is facilely realized using an electrolyte additive, ethylenediamine tetramethylenephosphonic acid, to substantially promote CO₂ electroreduction to CH₄ for commercial polycrystalline Cu. As a result, a stable CH₄ Faradaic efficiency of 64% with a partial current density of 192 mA cm^-2, thus enabling an impressive CO₂-to-CH₄ conversion rate of 0.25 µmol cm^-2 s^-1, is achieved in an alkaline flow cell. We believe our study will promote the exploration of electrochemical reconstruction and provide a promising route for the discovery of high-performance electrocatalysts.