One Bifunctional\nElectrocatalyst Derived from Nickel\nMOF for Urea Oxidation Reaction and Hydrogen Evolution Reaction

Abstract

Urea solution electrolysis can treat wastewater that\ninvolves urea\nby anodic oxidation reaction of urea (UOR) and can also produce clean\nhydrogen by cathodic hydrogen evolution reaction (HER) with lower\nvoltage. Therefore, it is of great importance to devise and synthesize\nnew bifunctional electrocatalysts for both UOR and HER. Herein, a\nnovel nickel metal–organic framework (Ni-bza, Hbza = 4-(1<i>H</i>-1,2,4-triazol-1-yl) benzoic acid) was constructed by a\nsolvothermal method, followed by the study of the Ni-bza-derived electrocatalyst\nNi-bza-T for UOR and HER applications; we found that Ni-bza-900 shows\nmore excellent performance in both UOR and HER. For UOR, at a current\ndensity of 10 mA·cm^–2, the overpotential can\nreach 1.38 V, and it needs a potential of 306 mV to achieve the same\ncurrent density for HER. Ni-bza-900 has smaller Tafel slopes of 176.8\nand 183.43 mV·dec^–1 in UOR and HER, respectively.\nBesides, Ni-bza-900 has a larger <i>C</i>_dl value,\nindicating a larger active area.