Surface Alloyed-Zn promotes stability of Cu-Au catalysts toward electrochemical CO2 reduction reaction

The electrochemical reduction of carbon dioxide (CO2RR) is a subject of great economic and social relevance, as it represents a promising solution for the storage of renewable energy in the form of valuable chemical compounds and fuels. Bimetallic Cu-Au catalysts show great promise in efficient CO2-to-CO electrochemical conversion, particularly within a less Au content. However, the stability issue of Cu-Au catalysts always places obstacles on the long-term CO2RR application due to the metal dissolution issue. Here, we report a trimetallic Cu-Au-Zn catalyst in which a few amounts of Zn are incorporated into the CuAu alloy shell to promote the stability of Cu-Au catalysts for electrochemical CO2RR. The incorporation of a low concentration of Zn not only modifies the CO binding affinity but also alters the catalytic properties of nearby CuAu through geometric and electronic effects. The few amounts of Zn play a vital role in suppressing the surface pits and potentially preventing preferential corrosion at specific sites during electrochemical reaction conditions, thus, the catalyst surface is stabilized. The as-synthesized Cu-Au-Zn catalyst (Zn = 3 at. % and Au < 20 at. %) exhibits a high CO2-to-CO activity, holding a CO faradaic efficiency of 82 % in 0.1 M KHCO3 saturated with CO2 at −0.8 V, and also shows superior stability with no obvious current and selectivity degradation in 10 h, as compared to the Cu-Au counterparts. It is revealed that the surface alloyed Zn significantly alleviates the movement of metal atoms, offers dissolution resistance, and improves both structural and performance stability while retaining excellent CO2-to-CO conversion. These important findings provide a strategy to strengthen the promising Cu-Au CO2RR catalysts with a high noble-metal utilization. More importantly, the addition of few amounts of metals and alloying can promote the stability of functional materials under reaction conditions.