Electronic optimization of heterostructured MoS2/Ni3S2 by P doping as bifunctional electrocatalysts for water splitting

Abstract

MoS2 is an excellent catalyst for hydrogen evolution reaction (HER) because of its close proximity to the optimum hydrogen adsorption free energy (ΔGH*). However, poor oxygen evolution reaction (OER) intrinsic activity, insufficient active sites, and poor conductivity hinder its application as a bifunctional electrocatalyst. Here, Ni3S2 is combined with MoS2 forming MoS2/Ni3S2 heterostructure due to its intrinsic OER activity and P is chosen as an anion dopant to optimize ΔGH* due to its near-thermoneutral H adsorption to explore the bifunctional performance of MoS2 based nanocomposites. The electronic configurations of Mo, Ni, and S on the interface are modulated by P doping, which optimizes their adsorption/desorption ability of intermediates. The synergistic effect of anion doping and heterostructure induces excellent catalytic activity in P40-MoS2/Ni3S2–5 (Mo to S molar ratio of 1:5 and 40 mg P dopants) with overpotentials of 142 mV for HER and 278 mV for OER at 100 mA cm−2 in 1.0 M KOH solution. The voltage of overall water splitting is 1.76 V using P40-MoS2/Ni3S2–5 as the anode and cathode. This work elucidates a method of optimizing the electronic structure by doping P anion in heterointerface, providing an avenue to boost the catalytic activity of non-noble metal-based catalysts.