One Bifunctional Electrocatalyst Derived from Nickel MOF for Urea Oxidation Reaction and Hydrogen Evolution Reaction

Urea solution electrolysis can treat wastewater that involves urea by anodic oxidation reaction of urea (UOR) and can also produce clean hydrogen by cathodic hydrogen evolution reaction (HER) with lower voltage. Therefore, it is of great importance to devise and synthesize new bifunctional electrocatalysts for both UOR and HER. Herein, a novel nickel metal–organic framework (Ni-bza, Hbza = 4-(1H-1,2,4-triazol-1-yl) benzoic acid) was constructed by a solvothermal method, followed by the study of the Ni-bza-derived electrocatalyst Ni-bza-T for UOR and HER applications; we found that Ni-bza-900 shows more excellent performance in both UOR and HER. For UOR, at a current density of 10 mA·cm–2, the overpotential can reach 1.38 V, and it needs a potential of 306 mV to achieve the same current density for HER. Ni-bza-900 has smaller Tafel slopes of 176.8 and 183.43 mV·dec–1 in UOR and HER, respectively. Besides, Ni-bza-900 has a larger Cdl value, indicating a larger active area.