Selective Electrocatalytic Reduction of Carbon Dioxide to Methane by Guanidine-based Metal-Organic Cage

In the context of energy shortages and environmental disasters, converting the greenhouse gas carbon dioxide into high-value carbon-based energy provides a practical pathway for achieving a sustainable artificial carbon cycle. However, integrating CO₂ capture with electrocatalysis remains challenging. Herein, we constructed a guanidine-based metal-organic cage as a homogeneous electrocatalyst to encapsulate and activate the adduct in-situ formed by CO₂ and ethanolamine, significantly lowering the reduction potential of CO₂ and achieving a record-low potential for CO₂ reduction to methane (0.16 V vs. reversible hydrogen electrode, RHE). Our research demonstrates that under the condition of -0.04 V vs. RHE, the Faradaic efficiency (FE) for methane reaches 69.8%, with a selectivity exceeding 99% for continuous operation over 18 hours.