Selective electrocatalytic carbon dioxide reduction with electrochemically stable frustrated Lewis pairs

High-energy-density fuels from carbon dioxide reduction are an ideal medium to store intermittent renewables. Lewis pairs are highly active for activation of small molecules. A challenge is to create electrochemically stable Lewis pairs on electrodes to exploit for small-molecule activation. Here, a strategy of protonating a surface oxidation layer of oxytropic alloys is proposed to create stable Lewis pairs by coordinatively unsaturated metal sites (Lewis acids) and metal hydroxyls (Lewis bases). We find that the element electronegativity and metal-hydroxyl stability are useful descriptors to screen available elements. The big electronegativity difference favors the element alloying, and the metal-hydroxyl stability indicates the possibility of formation of Lewis pairs. Lewis pairs tend to first capture and stabilize protons and then selectively activate carbon dioxide to various products, depending on the constituent of Lewis pairs. Our results verify that creating stable Lewis pairs is a promising material design concept for selective electrochemical reduction.