Engineering Isolated CoV–N x Sites and CoV Nanoparticles on Graphene: A Synergistic Platform for Oxygen Reduction Catalysis

The oxygen reduction reaction (ORR) has attracted significant interest as a key cathode reaction in emerging energy technologies, such as fuel cells and metal–air batteries, aimed at improving the present energy landscape and advancing sustainable energy solutions. Metal–nitrogen–carbon (M–N x –C) materials have been extensively investigated as potential alternatives to Pt-based catalysts due to their promising ORR activity. In this study, cobalt–vanadium isolated atoms/nanoparticles on nitrogen-doped graphene oxide (CV SA-NP /NG) were synthesized as an ORR catalyst. Different compositions of CV SA-NP /NG, besides the control samples, were prepared and analyzed by employing spectroscopy and electrochemical methods. Electrochemical results demonstrate that the best composition (CV(11) SA-NP /NG) exhibits high ORR catalytic performance, achieving an onset potential (E onset ) value of 0.92 and 0.79 V in 0.1 M KOH and 0.1 M HClO 4, respectively. CV(11) SA-NP /NG catalyzes the ORR via a four-electron transfer process, converting O 2 directly to OH – or H 2 O. The KSCN test confirms the presence of two types of active sites, namely CoV–N x and CoV nanoparticles.