Realising the activity benefits of Pt preferential (111) surfaces for ethanol oxidation in a nanowire electrocatalyst

Abstract

The commercialisation of direct ethanol fuel cells (DEFCs) is hindered by the low activity of the currently available electrocatalysts that are mainly carbon-supported nanoparticles (NPs). Here, we synthesised carbon-supported Pt nanowires (Pt/C NWs) by chemical reduction of metallic precursors at room temperature without using surfactants, templates, or stabilising agents. The synthesised Pt NWs were supported on high surface area carbon (Vulcan XC-72 R) with 40 wt%. Of metal loading concerning the support. The electroactivity of the synthesised NWs catalyst towards ethanol and CO (the dominant intermediate species) oxidation is investigated and tested in comparison with a commercial nanoparticle Pt/C electrocatalyst (named: Pt/C NPs). The electrooxidation of ethanol was investigated in acid media by CO-stripping, cyclic voltammetry, derivative voltammetry, chronoamperometry, steady-state polarisation curves, and in situ Fourier transform infrared spectroscopy (FTIR) experiments. The results showed that the synthesised Pt NWs are much more active than the Pt/C NPs catalyst, for both ethanol and CO-monolayer oxidation in acidic media. In situ FTIR data revealed that Pt NWs catalyst favours the formation of CO2 and acetic acid. This activity is mainly due to the existence of extended terraces, resulting in enhanced mobility of OHads and COads, facilitating the removal of COads from the catalyst surface and allowing better ethanol adsorption for further oxidation. Hence, 5-fold higher current density for ethanol oxidation is obtained. The NW morphology of Pt nanocatalysts results in very active materials towards ethanol oxidation and may provide a promising means of increasing the performance of anodes for DEFCs.