Electrocatalytic CO₂ Reduction toward C₂ Products on a Bimetallic CuZn-DAT Catalyst: Enhancement Mechanism of Zn and DAT on Ethanol Formation

The electrochemical reduction of CO2 to high-value C2 products, particularly ethanol, represents a promising strategy for mitigating greenhouse gas emissions and addressing climate challenges. However, the rational design of efficient electrocatalysts for this process remains hindered by insufficient activity, selectivity, and mechanistic understanding. So, this work developed a hierarchically structured copper–zinc bimetallic catalyst (CuZn-DAT) via a novel potential-step electrodeposition (PSE) method, employing diaminotriazole (DAT) as both a morphology-directing agent and electronic stabilizer. Multimodally comprehensive characterization (BET/SEM/TEM/XRD/EDS/ICP-OES/XPS) revealed a three-dimensional porous architecture with optimized electronic configurations, where Zn alloying narrowed the HOMO–LUMO gap, while DAT coordination suppressed Cu surface reconstruction. Electrochemical evaluations (CV/LSV/EIS/GC/1H NMR) demonstrated exceptional CO2-to-ethanol conversion performance, achieving a total Faradaic efficiency (FE) exceeding 75% at current densities above 50 mA cm–2, with ethanol dominating C2 products at 87% selectivity (FEethanol = 19.9%). Zn incorporation boosted FEethanol and partial current density by 325 and 600%, respectively, while subsequent DAT modification further enhanced these metrics by 194 and 292%. Mechanistic studies combined with density functional theory (DFT) calculations identified the accelerated *CO dimerization kinetics and stabilized *CO–CHO intermediates as critical factors. A dominant stepwise reaction pathway of CO2-to-ethanol conversion on the CuZn-DAT catalyst was established as CO2 (g) → *CO2 → *CO2– → *COOH → *CO → *CHO → *CO–CHO → *OHCH2CH3 → CH3CH2OH (l). This work establishes a dual-modification strategy (Zn alloying + organic stabilization) that advances the development of efficient electrocatalysts for sustainable CO2-to-ethanol conversion, providing fundamental insights into C–C coupling mechanisms and catalyst design principles for multicarbon product formation.