Promoting Effect of PbO on Ir Nanosurface Toward Ethanol Electrocatalytic Oxidation in Alkaline Media

Abstract

Metal-metal (hydr)oxide interfaces can promote the CO2 selectivity of ethanol oxidation reaction (EOR) due to so-called metal–oxide interaction (MOI). Here, we first show that the mixture of Ir and PbO species at the nanoscale can also form “bifunctional effect” sites, where the C–C bond of ethanol can be effectively cut at Ir sites to generate C1 intermediates, and nearby PbO species could provide oxygenated species. The as-prepared Ir-PbO/C catalysts with a mean metallic nanoparticle size of 2.6 ± 0.5 nm can greatly improve the activity, stability, and C1 pathway selectivity of EOR. Specifically, it exhibits superior mass activity of 1150 mA/mgIr in 1 M NaOH solution containing 1 M C2H5OH. Chronoamperometry tests show that the stability of Ir-PbO/C is also significantly improved compared with Ir/C. In situ electrochemical infrared absorption spectral results confirm that the addition of oxophilic PbO species could accelerate the oxidative removal of COad intermediates, thereby greatly improving catalytic performance. This study may give new insights into designing efficient anode catalysts for the direct ethanol fuel cells (DEFCs).