W₂C-Supported PtAuSn—A Catalyst with the Earliest Ethanol Oxidation Onset Potential and the Highest Ethanol Conversion Efficiency to CO₂ Known till Date

Abstract

The electrocatalytic behavior of a tungsten carbide-supported Pt(3 wt %)Au(3 wt %)Sn(10 wt %) catalyst (PtAuSn/W2C) is investigated toward the oxidation of ethanol at temperatures below 70 °C. Vulcan XC-72-supported Pt(3 wt %)Au(3 wt %)Sn(10 wt %) is used as a reference (PtAuSn/C). For a better understanding of the reaction mechanism, in situ techniques such as electrochemical mass spectrometry (EC-MS) and Fourier transform infrared spectroscopy (FTIRS) are employed. We show that PtAuSn/W2C has a higher electrocatalytic performance than PtAuSn/C, with a CO2 conversion efficiency of 6.5% detected at 0.65 V versus the reversible hydrogen electrode (RHE) at room temperature with on-line quantitative EC-MS measurements. FTIR spectra analysis and EC-MS during the ethanol oxidation reaction (EOR) show C–C bond breaking at the admission potential (0.05 VRHE) and an onset potential for the CO2 formation at E ≥ 0.20 VRHE. The CO tolerance of Pt nanoparticles in PtAuSn/W2C is improved by the presence of oxide species on W2C through a bifunctional mechanism, as well as the electronic charge transfer from the W2C support to the metallic nanoparticles through an electronic effect.