Sulfonated polybenzimidazole engineering defect-induced N, S-codoped carbon-supported Co3C hybrid composite as high-efficiency electrocatalyst for oxygen evolution reaction

The exploitation of efficient OER electrocatalysts has become the key to realize the commercial-application of H2 production from electrocatalytic water splitting. In this research, the novel defect-induced N, S co-doped carbon-supported Co3C nanoparticles were successfully fabricated as OER electrocatalyst by combination of wet-impregnation treatment of Co/sulfonated polybenzimidazole (sPBI) and subsequent thermal annealing treatment, which was denoted as Co3C/CNS-X (X=700, 800, 900) electrocatalyst. Among them, Co3C/CNS-800 delivered the more favorable architecture due to its large specific surface area, high dispersion of Co3C nanoparticles and especially the generation of abundant defects sites, which not only improved its conductivity and the amounts of electrocatalytically active sites but also imparted the extremely important functionality in accelerating the interfacial electron-transfer and facilitated the adsorption ability of intermediates, thus exerting the extraordinary activities for catalyzing OER. What's more, there were some evidences demonstrating the generation of the strong interfacial interactions through the Co-N coordination bonds and the formation of more pyridinic-N species though annealing treatment, which allowed the structural stability to be further strengthened and simultaneously gave impetus to the O2 release for the reduction of OER overpotential. In recognition of these approvable structural characteristics, the Co3C/CNS-800 exhibited the lowest overpotential of 300 mV at an anodic current density of 10 mA cm−2, and a small Tafel slope of 70 mV dec−1 in 1 M KOH electrolyte as well as a long durability.