Simultaneous heterostructure engineering and Mn doping modulation of Ni2P nanosheet arrays for enhanced electrocatalytic water splitting

Abstract

Efficient, low-cost, and stable electrocatalysts for water splitting are highly desirable. Herein, three-dimensional (3D) Ni2P nanosheet arrays were fabricated and simultaneously modulated by heterostructure engineering and Mn doping (Mn-doped Ni2O3/Ni2P and Mn-doped NixSy/Ni2P) via a facile hydrothermal reaction and subsequent phosphorization and sulfurization. Due to the Mn doping, synergistic effect in the heterostructures, and abundantly exposed active sites from the 3D-nanosheet arrays, Mn-doped Ni2O3/Ni2P and Mn-doped NixSy/Ni2P exhibit excellent properties for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The former achieves an excellent current density of −10 mA cm−2 at a low overpotential of 104 mV for HER, while the latter attains 100 mA cm−2 for OER at an ultralow overpotential of 290 mV and exhibits superior stability at 50 mA cm−2 for 160 h. Impressively, the Mn-doped Ni2O3/Ni2P//Mn-doped NixSy/Ni2P couple show high overall-water-splitting activity with a cell voltage of 1.65 V at 10 mA cm−2 and outstanding durability at 50 mA cm−2 for 120 h in an alkaline electrolyzer. This work presents an effective strategy to design and synthesize low-cost and highly active non-noble metal electrocatalysts for overall water splitting through the simultaneous application of heterostructure engineering, foreign-metal-atom doping, and a 3D-nanoarray structure. The strategy brings a paradigm shift toward the mass production of low-cost non-noble metal electrocatalysts for renewable energy devices. [Figure not available: see fulltext.].