Mn-Doped Crystalline\nNi₃S₂/Amorphous\nMoS₂ Core–Shell Nanorods as Bifunctional Electrocatalysts\nfor Highly-Efficient Overall Water Splitting

Abstract

Molybdenum disulfide (MoS₂), a typical earth-abundant\nmaterial, is an excellent candidate for the hydrogen evolution reaction\n(HER) and oxygen evolution reaction (OER), which fundamentally rely\non the regulation of the morphology and electronic structure of MoS₂. Herein, Mn-doped amorphous MoS₂ coated on Mn-doped\ncrystalline Ni₃S₂ nanorods (Mn–Ni₃S₂@MoS₂), rationally designed core–shell\nnanorods, have been fabricated via a facile one-step hydrothermal\nmethod as highly efficient bifunctional activities for HER and OER\nin alkaline solution. The target electrodes deliver a high current\ndensity of 100 mA cm^–2 at a low overpotential of\n187 and 310 mV for HER and OER, respectively, outperforming most MoS₂-based catalysts. Moreover, a water-splitting cell based on\nthe Mn–Ni₃S₂@MoS₂ electrode\nrequires a voltage of 1.45 V to reach a current density of 10 mA cm^–2, which is superior to the state-of-the-art one of\nthose based on noble metal Pt/C–NF∥RuO₂–NF\nand non-noble metal catalysts. The overall enhanced bifunctional catalytic\nperformance is mainly attributed to the abundant catalytically active\nsites provided by the Mn-doped amorphous MoS₂ and the fast\npathway for electron/proton transfer facilitated by the Mn-doped crystalline\nNi₃S₂ nanorods. The incorporated Mn dopants\nand assembled Ni₃S₂/MoS₂ heterostructure\neffectively regulate the electronic structure with redistributed charge\nwithin the core–shell Mn–Ni₃S₂@MoS₂ electrode.