Co5.47N/rGO@NF as a High-Performance Bifunctional Catalyst for Urea-Assisted Hydrogen Evolution

The hydrogen produced by water splitting is limited due to the high theoretical potential of the anode. So, the lower theoretical potential of the urea oxidation reaction (UOR) was selected. In this work, a highly efficient bifunctional catalyst, cobalt nitride doped with reduced graphene oxide nanosheets supported on Ni foam (Co5.47N/rGO@NF), was synthesized by hydrothermal and calcination methods for both UOR and hydrogen evolution reaction (HER). The morphology and composition of Co5.47N/rGO@NF was studied through XRD, XPS, SEM, TEM, HRTEM and elemental mapping. A parallel two-electrode electrolyzer (Co5.47N/rGO@NF parallel to Co5.47N/rGO@NF) was constructed for electrochemical testing. To drive 100 mA/cm(2), the voltage of Co5.47N/rGO@ NF parallel to Co5.47N/rGO@NF only 1.684 V is required, which is much lower than that of Pt/C parallel to IrO2 (1.875 V) and the current density can be maintained for at least 30 h. This demonstrates that its high activity and stability have commercial feasibility.