Unveiling the Role of Boron on Nickel-Based Catalyst for Efficient Urea Oxidation Assisted Hydrogen Production

Urea oxidation reaction (UOR) is an ideal alternative to oxygen evolution reaction (OER) for efficient hydrogen production but is immensely plagued by slow kinetics. Herein, a multilayer hole amorphous boron-nickel catalyst (a-NiBx) is fabricated through a simple chemical plating method, which displays intriguing catalytic activity toward UOR, demanding a low working potential of 1.4 V to reach 100 mA cm-2. The high performance is credited to the formation of metaborate (BO2-), which can promote the formation of high-oxidation-state NiOOH active phase and optimize the adsorption of urea molecules. This can be confirmed by the operando spectroscopy characteristics and density functional theory calculations. Consequently, the assembled electrolyzer utilizing NiBx as bifunctional catalysts exhibited splendid catalytic activity, requiring an evidently lower voltage of 1.66 V to reach a current density of 100 mA cm-2 and 1.57 V when using Pt/C as a cathode catalyst. Moreover, the assembled electrolyzer secured a robust stability of over 200 h, as well as a four times higher hydrogen production rate than traditional water electrolysis. An amorphous boron-nickel catalyst is synthesized using a simple and fast chemical plating method, replacing the traditional OER with a urea oxidation reaction (UOR) for hydrogen production. The excellent UOR performance is attributed to the in situ generated BO2- on the surface, which is responsible for the rapid formation of the NiOOH active phase and optimizing the absorption of urea molecules. image