Cobalt nanoparticles encapsulated in nitrogen-doped carbon as a bifunctional catalyst for water electrolysis

The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are important electrocatalytic processes in water electrolyzers. Identifying efficient non-precious metal catalysts for HER and OER remains a great challenge for applications in different kinds of electrolyzers. Herein, we report that cobalt nanoparticles encapsulated in nitrogen-doped carbon (Co@N-C) show high activity and durability for HER in a wide pH range and for OER in alkaline medium as a bifunctional catalyst. The HER and OER activities of Co@N-C are higher than those of multiwall carbon nanotube and iron nanoparticles encapsulated in nitrogen-doped carbon with a similar content of nitrogen. Electrolyzer prototypes using Nafion NRE-212 as electrolyte membrane and Co@N-C as cathode or anode catalyst are constructed, showing potential practical applications in water splitting.