Ag-Cu aerogel for electrochemical CO₂ conversion to CO

The current strategy of electrocatalytic CO₂ reduction reaction (eCO₂RR) to generate useful chemicals and hydrocarbons is supposed to effectively mitigate the greenhouse effect. The practical application for eCO₂RR in aqueous solutions, however, still was encumbered by its high overpotential, low activity and poor selectivity due to CO₂ mass transfer and intermediate stability. Electrocatalytic materials with reduced overpotential and high efficiency and selectivity are exploited for further development. Herein, Ag⁺ and Cu²⁺ precursors were co-reduced to generate Ag-Cu bimetallic aerogel after further freeze drying. Compared with Ag₁₀₀ aerogel, the optimal Ag₈₈Cu₁₂ can effectively decrease overpotential, improve selectivity and current density, and keep electrochemical stability. At -0.89 V vs. RHE, the Faraday efficiency reached 89.40% and the CO partial current density of -5.86 mA cm^-2 was obtained. The intrinsic property of metal aerogel (hydrophobic, hierarchical porous structure, conductivity), presence of rich grain boundaries and geometric effect and the introduction of Cu leading to improvement of adsorption between the catalyst and the *COOH intermediate in Ag₈₈Cu₁₂, contribute to the enhanced performance. Furthermore, the strategy of constructing metal aerogel will improve metal catalyst performance towards eCO₂RR and pave way for further industrial applications.