Enhanced electrochemical CO₂ reduction coupled with urea oxidation using bifunctional atomically dispersead CuNi catalysts

The electrochemical conversion of carbon dioxide (CO₂) into chemical fuels represents a promising approach for addressing global carbon balance issues. However, this process is hindered by the kinetic limitations of anodic reactions, usually the oxygen evolution reaction, resulting in less efficient production of high value-added products. Here, we report an integrated electrocatalytic system that couples CO₂ reduction reaction (CO₂RR) with urea oxidation reaction (UOR) using a bifunctional electrocatalyst with atomically dispersed dual-metal CuNi sites anchored on bamboo-like nitrogen-doped carbon nanotubes (CuNi-CNT), which were synthesized through a one-step pyrolysis process. The bifunctional CuNi-CNT catalyst exhibits a near 100% CO Faraday efficiency for CO₂RR over a wide potential range, and outstanding UOR performance with a negatively shifted potential of 210 mV at at 10 mA·cm⁻². In addition, we assemble a two-electrode electrolyzer using bifunctional CuNi-CNT-modified carbon fiber paper electrodes as both cathode and anode, capable of operating at a remarkably low cell voltage of 1.81 V at 10 mA·cm⁻², significantly lower than conventional setups. The study provides a novel avenue to achieving an efficient carbon cycle with reduced electric power consumption.