The escalating CO 2 emissions resulting from the overreliance on fossil fuels have positioned electrochemical CO 2 reduction (CO 2 RR) as a pivotal technology for sustainable carbon utilization. Relative to C 1 products, C 2 compounds offer superior utility due to their role as key intermediates in the synthesis of oxygenated chemicals, polymers, and long-chain hydrocarbon fuels. Among existing materials, copper-based catalysts are currently recognized as the most promising candidates for selective C 2 production. In this work, CuAl-layered double hydroxides (CuAl-LDH) with tunable Cu/Al molar ratios were synthesized via a coprecipitation method and employed as precursors for subsequent material transformation. Optimized CuAl-LDH was then subjected to liquid-phase reduction to fabricate Cu/Cu 2 O nanomaterials, with hydrothermal temperature and duration systematically varied as critical synthetic parameters. The resultant Cu/Cu 2 O sample (denoted 16-SHPCR), obtained using sodium hypophosphite monohydrate as the reducing agent under hydrothermal conditions at 160 °C for 16 h, exhibited superior electrocatalytic performance toward CO 2 RR. The primary reduction products included CO, C 2 H 4 , CH 4 , and H 2 , achieving a combined Faradaic efficiency (FE) exceeding 80%. Notably, the FE for C 2 H 4 reached 35%, while that of the competing hydrogen evolution reaction (HER) was suppressed to below 25%. The material demonstrated favorable stability, with only a 9.5% increase in charge transfer resistance over a 60-min operation period, and delivered a current density of 61 mA cm −2 at − 1.0 V versus the reversible hydrogen electrode (RHE). Comprehensive characterization and analysis revealed a pronounced synergistic interaction between metallic Cu 0 and Cu + species on the catalyst surface. A lower Cu/Cu 2 O ratio was found to stabilize the Cu + active sites, thereby enhancing CO 2 activation and facilitating the C–C coupling pathway during the catalytic process.
Liu et al. (Fri,) studied this question.