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 H2 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 (E10/1,000 = 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 H2 production through urea‐assisted water electrolysis.

Keywords

• carbon‐encapsulated structure
• catalyst
• hydrogen production
• large current density
• urea‐assisted water electrolysis