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

MoS2 is an excellent catalyst for hydrogen evolution reaction (HER) because of its close proximity to the optimum hydrogen adsorption free energy (AGH*). 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 AGH* 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.