Surface engineering of Ni2P/CoP nanosheet heterojunctions by the formation of F-doped carbon layers for boosting urea-rich water electrolysis

Abstract

It's highly desirable but still challenging to design bifunctional non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) with high activity and boosted mass transport, especially under large-current densities. Hence, a novel 3D reticular heterostructure nanosheet arrays are fabricated (Ni2P/CoP/P,F–C) through coupling the F-doped carbon to realize urea-rich water electrolysis. The interface of carbon doping F can effectively enhance the conductivity and stability of Ni2P/CoP heterojunctions along with possible changes in surface hydrophobicity to accelerate release of generated bubbles under large-current densities. Benefiting from tailored d-band center of CoP nanosheet arrays and well-designed hydrophilic-superaerophobic feature, the elaborated Ni2P/CoP/P,F–C electrode shows brilliant electrocatalytic HER (198 mV) and UOR (251 mV) performance at 100 mA cm−2 current density. Meanwhile, the assembled alkaline urea-rich water electrolyzer with Ni2P/CoP/P,F–C as both the cathode and anode present ultralow cell voltages of 1.57 V to achieve 100 mA cm−2 with long-time stability. This work will promote research interest in material design for energy conversion technologies and urea-assisted hydrogen production.