Anion-regulation engineering toward Cu/In/MOF bimetallic electrocatalysts for selective electrochemical reduction of CO2 to CO/formate

The conversion of carbon dioxide (CO₂) into high-value added energy fuels and chemicals (CO, formate, C₂H₄, etc.) through electrochemical reduction (eCO₂R) is a promising avenue to sustainable development. However, low selectivity, barren activity and poor stability of the electrodes hinder the large-scale application of eCO₂R. Herein, we reported a copper-indium-organic-framework (CuIn-MOF) based high-performance catalyst for eCO₂R. Electrochemical measurement results reveal that CuIn-MOF exhibits high Faradaic efficiency (FE) of CO and formate (300 mV, FE_CO = 78.6% at −0.86 V vs. RHE, FE_HCOO⁻ = 48.4% at −1.16 V vs. RHE, respectively) in a broad range of current density (20.1–88.4 mA cm⁻²) with long-term stability (6 h) for eCO₂R in 0.5 M KHCO₃ electrolyte solution. Specifically, through anion-regulation engineering, SO₄²⁻ anion precursor is more beneficial for the formic acid generation than NO₃⁻ anion precursor; while for SO₄²⁻ anion precursor, Cu plays a positive regulating role in eCO₂R to CO compared to In. Additionally, the high performance in a home-made eCO₂R reactor derives benefit from enhanced intrinsic activity and charge re-distribution can be attributed to the formation of In-doped Cu layer.