New ammonia-based CO₂ capture product (NH₄HCO₃) for electrochemical reduction of single-atom Cu catalyst to CO

The integration of CO₂ capture and electrochemical CO₂ reduction reaction (ECO₂RR) enables low-energy conversion of CO₂ from the emission end to the product end. To effectively address issues such as the consumption of products from new ammonia-based carbon capture technology and the high energy consumption of CO₂ regeneration, this study prepared a Cu single-atom catalyst (SACu/CNTs) and proposed using NH₄HCO₃ as the electrolyte for ECO₂RR. The Cu-N₃ structure of the catalyst is confirmed by X-ray absorption fine structure testing. Benefiting from the double hydrolysis characteristics of NH₄HCO₃ solution, Faraday efficiency (FE) of 60 % for CO is achieved at −1.4 V. In-situ Raman spectroscopy confirms that the adsorption of NH₄⁺ on the catalyst and the coverage of H⁺ resulted in suboptimal CO selectivity. By dynamically regulating the valence state of Cu using a pulsed potential to avoid NH₄⁺ and H⁺ coverage, FE of CO is increased to 78 %. Density functional theory (DFT) calculations indicate that the η_CO of the Cu-N₃V-SAC structure of the catalyst is 1.161, indicating a suitable adsorption strength for CO. The decrease in the coordination number of N enhances the adsorption strength for *COOH, the rate-determining step of the reaction shifts from CO₂ → *COOH to *CO → CO. Using the carbon capture product NH₄HCO₃ as the electrolyte for ECO₂RR demonstrates potential application prospects. This study provides new ideas and theoretical support for catalyst design in integrated carbon capture and utilization (ICCU).