Highly-active copper oxide/copper electrocatalysts induced from hierarchical copper oxide nanospheres for carbon dioxide reduction reaction

Novel hierarchical copper oxide (CuXO) nanosphere particles are synthesized, and then coated onto gas diffusion layer (carbon) to form a working electrode for catalyzing CO2 electroreduction. When applying a negative voltage to the working electrode, the metal Cu nanoparticles which are induced by the CuXO nanospheres appear. CuXO and metal Cu together form the CuXO/Cu nanocatalysts which show high catalytic activity for CO2 electroreduction. The morphology, composition, crystal structure and surface area of the CuXO/Cu electrocatalysts are characterized using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The CuXO/Cu nanoparticles are tested as the catalysts for CO2 electroreduction using cyclic voltammetry and linear sweep voltammetry in CO2-saturated 0.5 M KHCO3 aqueous electrolyte. It is found that the CO2 electroreduction activity is highly improved using this CuXO/Cu nanocatalyst, which remains stable during 20 h of electrolysis, along with the high selectivity with a ∼62% of Faradaic efficiency for formate production. Detailed kinetic information relevant to the catalysis is also discussed.