Electrodeposited copper-cuprite layers modified with rGO for light-supported conversion of CO2 to methane and ethylene

Cu-Cu2O-rGO composite layers were electrodeposited for the first time from alkaline copper(II) lactate-based electrolytes containing dispersed rGO flakes. The properties of electrodeposited composite materials are strongly affected by applied potentials. Obtained layers were investigated towards their catalytic activity in electro- and photoelectrochemical artificial CO2-based synthesis of hydrocarbons. The effect of applied potential on the morphology, crystallographic structure, band gap, and conduction and valence band location was investigated. The catalytic performance of the electrodeposited layers was analyzed in CO2-saturated KHCO3 electrolyte under the dark and at light illumination applying different conversion potentials. The stability of the obtained layers was analysed based on XPS and XAS results. Maximal Faradaic efficiencies for methane and ethylene formation were achieved in the presence of light and amounted to 10 and 9.91%, respectively. Reported results indicate that the presence of rGO in deposited layers significantly affects the band structure of electrodeposited layers. It was also observed that even slight modification of electrodeposition or conversion potential results in noticeable differences in Faradaic efficiency corresponding to hydrocarbons formation.