Low-Loaded Pt Nanoparticles Supported on Electrochemically Exfoliated Graphene as a Sustainable Catalyst for Electrochemical Ethanol Oxidation

Abstract

Securing ever-increasing energy demands while reducing resilience on fossil fuels is a major task of modern society. Fuel cells are devices in which the chemical energy of various fuels can be converted into clean electricity. Direct ethanol fuel cells (DEFC) are increasingly popular for their eco-friendliness and significantly easier liquid fuel manipulation compared to hydrogen-fed fuel cells. Carbon-supported Pt nanoparticles are considered reference catalysts for fuel oxidation in DEFCs. Several challenges hinder DEFC commercialization: high Pt-loading, Pt poisoning by CO intermediates, and the instability of the Pt and carbon supports. This work demonstrates an efficient electrocatalyst for ethanol oxidation reaction (EOR) composed of Pt nanoparticles supported on electrochemically exfoliated graphene (Pt/el-rGO). Graphene was obtained through anodic electrochemical exfoliation using graphitic tape as the anode, while Pt nanoparticles were synthesized using chemical reduction with formic acid. As-obtained Pt/el-rGO with only 7.5 wt.% Pt was characterized using TEM, SEM, and XPS. Pt/el-rGO exhibited notably higher EOR catalytic activity in an alkaline electrolyte than the Pt/C benchmark. This enhancement can be linked with the functional groups present on the graphene support, which facilitate ethanol dehydrogenation as the first step in the EOR mechanism and thus enhance reaction kinetics on Pt-active sites.