Effective Electrocatalytic Hydrogen Evolution in Neutral Medium Based on 2D MoP/MoS₂ Heterostructure Nanosheets

Abstract

The hydrogen evolution reaction (HER) in the neutral medium can avoid the problems caused by strong acid (bases) media and thus is promising for practical application. The suitable catalyst in the neutral medium for HER requires good conductivity for decreasing ohm resistance, porous structures for weakening diffusion resistance, and plentiful active sites, but its synthesis remains a challenge. Here, the 2D MoP/MoS₂ heterostructure nanosheets rather than common anion doping supported on carbon cloth (CC) was designed to meet the above criteria. The catalyst only needs a low overpotential of 96 mV to achieve a current density of 10 mA cm^-2 (η₁₀) for HER in the neutral medium (without <i>iR</i> correction), which is much lower than 199 mV of the bare MoS₂. The good performance is ascribed to plentiful active sites on the heterointerface of MoP/MoS₂ for activating H₂O, good conductivity of MoP and CC for electron transfer, and pores surrounded by MoP/MoS₂ facilitating mass transfer as shown by XPS and density functional theory calculations. The catalyst also exhibits outstanding activity in alkaline (η₁₀ of 54 mV) and acid (η₁₀ of 69 mV) media. The cells by coupling the MoP/MoS₂ cathode with a NiFe-LDH anode can deliver a current density of 10 mA cm^-2 at 1.51 V in 1 M KOH and 1.98 V in 1 M PBS. The effective overall water splitting can be driven by a solar panel (1.51 V), implying its ability to store solar energy as H₂ energy.