Strong electronic coupling of CoNi and N‐doped‐carbon for efficient urea‐assisted H₂ production at a large current density

Abstract

Abstract Exploiting efficient urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) catalysts are significant for energy‐saving H 2 production through urea‐assisted water electrolysis, but it is still challenging. Herein, carbon‐encapsulated CoNi coupled with CoNiMoO (CoNi@CN‐CoNiMoO) is prepared by solvothermal method and calcination to enhance the activity/stability of urea‐assisted water electrolysis at large current density. It exhibits good activity for UOR ( E 10/1,000 = 1.29/1.40 V) and HER ( E −10/−1000 = −45/−245 mV) in 1.0 M KOH + 0.5 M urea solution. For the UOR||HER system, CoNi@CN‐CoNiMoO only needs 1.58 V at 500 mA cm −2 and shows good stability. Density functional theory calculation suggests that the strong electronic interaction at the interface between NiCo alloy and N‐doping‐carbon layers can optimize the adsorption/desorption energy of UOR/HER intermediates and accelerate the water dissociation, which can expedite urea decomposition and Volmer step, thus increasing the UOR and HER activity, respectively. This work provides a new solution to design UOR/HER catalysts for H 2 production through urea‐assisted water electrolysis.