Cobalt nanoparticles embedded in porous N-rich carbon as an efficient bifunctional electrocatalyst for water splitting

Exploring efficient non-precious electrocatalysts with dual functionality for working in the same electrolyte towards both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for developing various devices for conversion, storage and usage of renewable energy. In this communication, we report a novel bifunctional electrocatalyst based on cobalt nanoparticles (NPs) embedded in porous N-rich carbon (PNC/Co) derived from a cobalt-containing metal–organic framework, which can serve as both active cathode and anode materials to drive the overall water splitting in alkaline media for the simultaneous electrogeneration of hydrogen and oxygen gases. In 1.0 M KOH electrolyte, the PNC/Co achieves small overpotentials at a current density of 10 mA cm−2 and yields high faradaic efficiency towards both the HER and OER. When fabricated as an alkaline water electrolyzer, the bifunctional PNC/Co affords 10 mA cm−2 at a cell voltage of 1.64 V.