Copper Catalysts Inherit and Retain Precatalyst Morphology in Extended CO Electroreduction to n-Propanol.

Copper catalyst morphology, faceting, and oxidation state are each known to impact selectivity in the electroreduction of CO. Copper oxide precatalysts are synthesized using flash Joule heating and rapid cooling, and it is observed that temperature ramp rates can be used to control morphology, enabling us to implement ≈10 nm-sized intragrain features within ≈35 nm grains. It is found that the structural features of the precatalysts are substantially transferred to Cu catalysts that are formed when they are employed in CO electroreduction in a membrane electrode assembly electrolyzer. The catalysts achieve ≈35% faradaic efficiency to n-propanol, among the highest selectivities to C from monometallic Cu. Both selectivity and morphology are retained following 330 h of operation at 100 mA cm. CO dilution studies reveal that catalysts with similar faceting, but smaller grain sizes, exhibit n-propanol selectivity that increases with CO concentration, suggesting that grain interfaces contribute to CO coverage and C-C coupling. Complementary operando Raman spectroscopy shows that reducing grain size enables higher CO coverage, suggesting that structural features enhancing linear CO adsorption are correlated with improved selectivity to C.