Electrochemical control of the morphology and functional properties of hierarchically structured, dendritic Cu surfaces

Electrodeposited dendritic copper foams have been extensively studied as an electrocatalyst for CO2 reduction reaction (CO2RR). Many parameters, such as dendrite size, porosity, pore size, and crystal faceting, define the hierarchical properties of these structures and their subsequent bubble evolution and CO2RR capabilities. Here we studied the effects the electrodeposition conditions (potential, pH) have on the resulting crystallinity, microstructure, and macroporosity of the copper foam. We characterized these morphological differences and the corresponding effects on electrocatalytic activity. We showed that the composition of the electrodeposition bath can have significant effects on the mechanics of bubble formation and detachment at the surface during hydrogen evolution reaction (HER) in acidic solutions. Similarly, the electrodeposition conditions for the synthesis of the foam affected the product selectivity during CO2RR electrocatalysis. Foams deposited in alkaline electrodeposition solutions showed high faradaic efficiency and specificity towards C2H6, an uncommon product of CO2RR, at modest applied potentials (-0.8 V vs. RHE).