CO2 electroreduction at AuxCu1-x obtained by pulsed laser deposition in O2 atmosphere

AuxCu1-x thin films were synthesized by pulsed laser deposition (PLD) and their electrocatalytic properties towards CO2 reduction in aqueous solution were assessed. The presence of an O-2 atmosphere during the PLD process modified the chemical nature of the resulting AuxCu1-x films, with different oxide types identified by X-ray photoelectron spectroscopy. The impact of these oxides, and of the Cu/Au stoichiometry, on the partial current density and conversion efficiency were assessed. The formation of AuxCu1-x alloy thin films and/or the introduction of an O-2 atmosphere during deposition does not yield to any marked increase of the formation of carbonaceous compounds, and CO and H-2 were the only two products formed, along with formate detected in trace amounts (< 1%). Oxide-derived Au catalysts obtained by PLD under O-2 atmosphere do not alter CO2 selectivity towards CO formation. High copper content catalysts deposited in vacuum exhibit the lowest overall CO FE%, while increasing the Au content enhances it. The same trend is observed for AuxCu1-x catalysts deposited under 2 and 220 mTorr O-2, aside from the fact that increasing Cu content under high O-2 pressure has a less negative influence on CO FE%. (C) 2017 Elsevier Ltd. All rights reserved.