Composite copper oxide–copper bromide films for the selective electroreduction of carbon dioxide

Composite copper oxide–copper bromide films were electrodeposited on gas diffusion layer (GDL) supports under controlled potential from aqueous copper salt solutions in the presence of a complexing/surfactant agent such as lactate. The solution pH was adjusted to target simultaneous deposition of cubic nanostructures composed of copper, oxygen, and bromine elements. The film composition and morphology were carefully tuned for enhanced electrochemical conversion of CO2 to hydrocarbons. Hydrocarbon products, predominantly ethylene and minor amounts of methane, ethane, and propylene were observed along with inevitable H2 co-generation. Importantly, CO gas was not detected during CO2 electrolyses. Low temperatures (3–5 °C) enhanced the conversion of CO intermediate to C2H4. The durability and electroactivity of these composite films were maintained for extended periods (up to 10 h) of CO2 electrolysis by periodic in situ application of anodic pulses to regenerate the cathode surface.