In Situ Carbon-Encapsulated Copper-Doped Cerium Oxide Derived from MOFs for Boosting CO₂‑to-CH₄ Electro-Conversion

Electrochemical CO₂ reduction reaction offers enormous potential for achieving carbon neutrality by converting CO₂ back into value-added chemicals and fuels. In the quest to resolve its current problem of poor selectivity or low current density toward one specific product, we propose a feasible strategy to develop a carbon-encapsulated copper-doped cerium oxide composite (Cu/CeO₂@C) by one-pot pyrolysis of metal–organic framework (MOF) precursors. The optimal Cu/CeO₂@C achieves a high CH₄ Faraday efficiency of 80.3% and a large CH₄ partial current density of 138.6 mA cm^–2. We demonstrate that the enhanced activity is attributed to the synergistic effect of Cu/CeO₂ and in situ-formed carbon with robust channels to assist charge transfer. Operando attenuated total reflection–infrared spectroscopic characterization reveals that the carbon can strengthen the adsorption of intermediates on active sites, facilitating the reaction kinetics and ultimately improving the selectivity of CH₄.