Phase‐Engineering of 1T/2H Molybdenum Disulfide by Using Ionic Liquid for Enhanced Electrocatalytic Hydrogen Evolution

Abstract

AbstractTwo‐dimensional (2D) molybdenum disulfide (MoS2) has been regarded as an attractive non‐precious‐metal electrocatalyst for the hydrogen evolution reaction (HER). Engineering the crystal phase of MoS2 to activate the basal planes/edges and simultaneously improve the electronic conductivity is currently an effective strategy for enhancing its HER activity. Herein, we report a facile and efficient hydrothermal route to prepare 1T/2H‐MoS2 catalysts using ionic liquid (N‐butyl pyridinium bromide, [BPy]Br) as a structure‐directing agent, where the large steric hindrance of [BPy]Br and the mutual π‐stacking interaction induce the phase transition of MoS2 from 2H to the 1T phase. By adding a suitable amount of [BPy]Br in the reaction system, the portion of the 1T phase in 1T/2H‐MoS2 was increased, which can expose more active sites on its basal planes/edges as well as facilitate charge transfer for the HER. Consequently, 1T/2H‐MoS2 with the 1T portion of 91.9 % exhibits a significantly enhanced HER activity compared to that of the MoS2 synthesized without the aid of [BPy]Br, in terms of a lower Tafel slope of 59 mV dec−1. This synthesis strategy provides valuable guidance for designing the phase structure of MoS2‐based electrocatalysts to achieve high HER efficiency.