Substituting low theoretical potential of the urea oxidation reaction (UOR) for the high theoretical potential of water splitting at the anode (oxygen evolution reaction) is meaningful for hydrogen energy storage and conversion. In this work, a bifunctional catalyst, cobalt nitride nanoflakes supported on Ni foam (CoN NF/NF), was synthesized for both UOR and hydrogen evolution reaction (HER). A two-electrode electrolyzer (CoN NF/NF||CoN NF/NF) was constructed. To drive 100 mA/cm2, the voltage of CoN NF/ NF||CoN NF/NF only 1.698 V is required, which is much lower than that of Pt/C||IrO2 (1.860 V) and the current density can be maintained for 30 h.
