1T/2H Mixed Phase MoS₂ Nanosheets Integrated by a 3D Nitrogen-Doped Graphene Derivative for Enhanced Electrocatalytic Hydrogen Evolution

Abstract

Molybdenum disulfide (MoS₂) has become one of the most promising non-platinum-based electrocatalysts for the hydrogen evolution reaction (HER) because of its unique layered structure. However, the catalytic performance of the thermodynamically stable MoS₂ is hindered by its poor conductivity and scarce active sites. We developed a 3D porous N-doped graphene derivative-integrated metal-semiconductor (1T-2H) mixed phase MoS₂ (MNG) using urea as a doping reagent. The highly exposed active sites were achieved by inducing the phase transition of MoS₂ from 2H phase to 1T phase and the inclusion of highly N-incorporated reduced graphene oxide, both of which were simultaneously realized by optimizing the concentration of the doping reagent. Moreover, the charge/proton transfer was enhanced by the well-designed porous architecture and hydrophilic 1T-MoS₂. With these advantages, the optimized MNG-40 catalyst has a small overpotential of 157 mV at a cathodic current density of 10 mA cm^-2, a relatively low Tafel slope of 45.8 mV dec^-1, and an excellent stability. This work represents a new strategy to design higher-performance HER catalysts and provides new insights into the structural regulation of metal composite transitions.