Enhanced electrocatalytic activity of NiCoP/Ni <sub>5</sub> P <sub>4</sub> @NiFe-LDH catalysts via Ir doping and oxygen vacancy engineering
Zhengxi Zhao, Liwei Sui, Ziqi Wang, Shiwei Song, Jian Wang, Yucai Li, Depeng Zhao, G.F. Li, Lihua Miao
Abstract
Alkaline water electrolysis offers a promising route for large-scale hydrogen production, but its efficiency is limited by the sluggish kinetics of both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, we designed a hierarchical composite electrocatalyst comprising iridium-doped nickel-cobalt phosphide nanoparticles (Ir-NiCoP/Ni5P4) encapsulated within nickel-iron layered double hydroxide nanosheets (NiFe-LDH). Oxygen vacancies (OV) were engineered on the surface via sodium borohydride reduction, yielding an optimized catalyst denoted as Ir-NiCoP/Ni5P4@NiFe-LDH-1-OV. The optimized catalyst delivers low overpotentials of 52.7 mV for HER and 197.3 mV for OER at 10 mA cm-2 and maintains remarkable stability over 100 h for overall water splitting. Moreover, the Ir-NiCoP/Ni5P4@NiFe-LDH catalyst exhibits overpotentials of 76.7 and 101.3 mV for HER and the ammonia oxidation reaction A in 1 M KOH + NH3·H2O, respectively.