Highly selective electrocatalytic reduction of CO2 to ethane over a petal-like Zn(OH)2/Cu2+1O/Cu foam catalyst at low overpotentials

Abstract

The electrocatalytic CO₂ reduction reaction (ECO₂RR) is a crucial process for converting CO₂ into value-added chemicals. Achieving high efficiency in the synthesis of ethane through the ECO₂RR remains a challenging task. In this work, we developed a Cu₂₊₁O species combined with Zn(OH)₂ loaded on a copper foam catalyst, denoted as Zn(OH)₂/Cu₂₊₁O/CF, presenting a lamellar structure, which offers high selectivity to ethane at low overpotentials. Typically, at −0.3 V (vs. RHE), the catalyst showed high activity, excellent stability, and a high ethane faradaic efficiency(FE_C2H6) of 67.8% with a current density of 5.56 mA cm⁻² in 0.1 M KCl electrolyte. The FE_C2H6 still reached 25.4% with a higher current density of 29.40 mA cm⁻² at −0.5 V (vs. RHE). These values are much higher than those of state-of-the-art catalysts for ethane formation at low overpotentials. The catalytic performances were derived from the metal defects in Cu₂₊₁O offering abundant Cu⁺ and Cu²⁺ valent species, which could be stabilized by the Zn(OH)₂. They achieved excellent stability in a long-term operation for three days. The catalytic performances and catalyst's structure were systemically investigated via diverse characterization techniques, and the formation of ethane involved *CO, *COOH, and *CO–*CH₂ intermediates, which were confirmed by using in situ Raman tests and DFT calculations. This work offers an essential reference in designing and constructing efficient Cu-based catalysts with stable Cu⁺ and Cu²⁺ valences, especially in reactions such as electrolytic CO₂ reduction.