Surface and Interface Engineering in Copper-Based Bimetallic Materials for Selective CO₂ Electroreduction

The electrochemical CO₂ reduction reaction (CO₂RR) can couple carbon-capture storage with renewable energy to convert CO₂ into chemical feedstocks. For this process, copper is the only metal known to catalyze the CO₂RR to hydrocarbons with adequate efficiency, but it suffers from poor selectivity. Copper bimetallic materials have recently shown an improvement in CO₂RR selectivity compared with that of copper, such that the secondary metal is likely to play an important role in altering inherent adsorption energetics. This review explores the fundamental role of the secondary metal with a focus on how oxygen (O) and hydrogen (H) affinity affect selectivity in bimetallic electrocatalysts. Here, we identify four metal groups categorized by O and H affinities to determine their CO₂RR selectivity trends. By considering experimental and computational studies, we link the effects of extrinsic chemical composition and physical structure to intrinsic intermediate adsorption and reaction pathway selection. After this, we summarize some general trends and propose design strategies for future electrocatalysts. Global consumption of fossil fuels is driving anthropogenic climate change and depleting reserves. To stem these environmental problems and secure future energy commodities, the electrochemical CO₂ reduction reaction (CO₂RR) presents an ideal solution because it can couple carbon-capture storage technology with renewable energy to convert atmospheric CO₂ into useful chemical feedstocks. Efficient catalysts are required to drive this process with adequate energy efficiency and product selectivity. In this review, we discuss how surface and interfacial engineering can be used as a strategy for designing copper alloy and bimetallic materials for selective CO₂ reduction to CO or hydrocarbons and alcohols. Developing selective catalysts is extremely important for the electrochemical reduction of CO₂ to fuels. For this process, copper can produce hydrocarbon products such as methane but suffers from poor selectivity. Alloying copper with another metal could modify its inherent properties and improve its selectivity. This review explores the fundamental role of the secondary metals and whether their oxygen and hydrogen adsorption properties can determine CO₂ reduction selectivity. Based on these findings, strategies for the design of selective copper-based catalysts are proposed.