One-pot gamma radiolysis synthesis of a graphene oxide-supported cobalt oxyhydroxide electrocatalyst for oxygen reduction reaction

Abstract

In this work, high-performance non-platinum group metal (non-PGM) electrocatalysts for oxygen reduction reaction (ORR) are synthesized from graphene oxide-supported cobalt oxyhydroxide nanoparticles via a one-pot gamma radiolysis method. Investigations are conducted into how cobalt precursor concentration and the amount of gamma radiation affect the electrocatalysts' ability to perform oxygen reduction reactions as well as their physicochemical characteristics. Results show that the electrocatalyst prepared with the 0.1 M cobalt precursor and gamma radiation dose of 25 kGy has an advantage over the other samples in displaying good oxygen reduction activity. The characterization results of the synthesized electrocatalyst obtained through field-emission scanning electron microscopy–energy dispersive spectroscopy and X-ray diffraction combined with Rietveld refinement confirm the presence of nanosized cobalt oxyhydroxide particles that are evenly distributed on the surface of graphene oxide. ORR results show that the electrocatalyst has an onset potential of 0.90 V (vs. the reversible hydrogen electrode or RHE), a half-wave potential of 0.75 V (vs. RHE), a low peroxide yield of 7.08%, and an electron transfer number of 3.86, indicating a four-electron transfer path-way in the ORR process. This work provides an alternative facile means to mass-produce competitive non-PGM ORR electrocatalysts for fuel cell applications.