Tuning morphology and interfacial bonding environment of three-phase Ni3S2/MoS2/Co2P heterojunction for urea-assisted energy-saving hydrogen production at ampere-level current density

A major significance persists in the construction of cost-effective electrocatalysts possessing both outstanding activity and robust durability for water and urea electrolysis, which is essential for realizing energy-saving hydrogen evolution. However, it is still challenging to explore bifunctional electrocatalysts under ampere-level current density. Herein, we report the construction of a three-phase heterojunction electrocatalyst with bifunctional activity toward both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR), achieved through the deliberate tuning of morphological features and electronic configurations. Through local bonding environment engineering at the heterointerface, the unique heterostructure effectively accelerates electron transfer and interfacial interactions, leading to significantly improved reaction kinetics and intrinsic electrocatalytic activity. Density functional theory (DFT) calculations reveal that the multi-heterostructure promotes electron migration and interfacial coupling via the concerted regulation of the electronic configuration, d-band center position, and density of states (DOS). These modifications collectively lower the chemisorption free energies of reaction intermediates, thereby accelerating the dissociation of both water and urea molecules. As a result, the heterojunction electrocatalyst exhibits ultralow potentials of −0.198 and 1.41 V to reach 1000 mA cm −2 for HER and UOR, respectively. Notably, when employed as a urea-assisted electrolyzer, the system achieves a cell voltage of 1.58 V at 500 mA cm −2 , which is 200 mV less than that required for conventional water electrolysis. Furthermore, the UOR-HER electrolyzer exhibits robust operational stability, sustaining 500 mA cm −2 for 100 h without significant degradation. Collectively, this study establishes a novel and practically viable route toward low-energy-consumption hydrogen production. A self-supported three-phase Ni₃S₂/MoS₂/Co₂P heterostructure nanoarray on nickel foam for efficient HER and UOR. Download: Download high-res image (136KB) Download: Download full-size image