Electrochemically exfoliated graphene as support of platinum nanoparticles for methanol oxidation reaction and hydrogen evolution reaction

Abstract

To enhance the utilization efficiency of platinum (Pt) in electrochemical energy conversion, the precise selection of support materials presents a highly promising strategy. We have developed an efficient and stable bifunctional catalyst for methanol oxidation (MOR) and hydrogen evolution (HER) reaction in an alkaline medium. The Pt-based electrocatalyst, denoted as Pt/e-rGO with low Pt loading was successfully synthesized using graphene sheets as the support via chemical reduction using formic acid as the reducing agent. Graphene sheets are obtained by anodic electrochemical exfoliation of graphite tape. Significant enhancement of intrinsic activity toward MOR and HER was achieved for Pt/e-rGO compared to the commercial Pt/C catalyst. Structural characterization was performed by TEM, SEM and XPS. XPS analysis shows that the graphene is highly reduced. TEM analysis unveiled that the majority of the Pt nanoparticles (NPs) exhibit a diameter in the range of 4-5 nanometers, which is significant because the efficiency of electrooxidation of methanol on supported Pt NPs shows a strong dependence on particle size distribution. Catalyst activity was studied by cyclic voltammetry and linear sweep voltammetry in 0.1M KOH. Electrochemical active surface area (ECSA) was measured by CO-stripping voltammetry and estimated to be 67.93 m2 /g. Current density of 11.28 mA/cm2 ECSA at 0.82 V vs. RHE for MOR is achieved. Onset potential for MOR is 0.55 V vs. RHE. Meanwhile, for HER overporential at the current density -10 mA/cm2 ECSA was 119 mV.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi