Large-scale controlled synthesis of porous two-dimensional nanosheets for the hydrogen evolution reaction through a chemical pathway

Abstract

Molybdenum disulfide (MoS₂) is an extensively studied promising non-noble catalyst because of its remarkable performance for the hydrogen evolution reaction (HER). However, the primary factors that affect its catalytic activity have not been analysed comprehensively and quantitatively; this impedes the further design and development of MoS₂-based electrocatalysts. Herein, using novel porous MoS₂ nanosheets prepared via a controlled and scalable KOH-assisted exfoliation pathway, we methodically studied the contributions of bore edge active sites to the catalytic activity towards the HER. To make the preparation safer, 2H-MoS₂ instead of 1T-MoS₂ that needs to be prepared with butyllithium has been chosen to synthesize porous MoS₂ nanosheets. A comparative study revealed that the overpotential of porous MoS₂ nanosheets exhibited an extreme point, which was predominantly due to the different densities of bore edge active sites derived from different quantities of KOH. Amazingly, the HER performance of MoS₂ nanosheets experienced the most obvious improvement after these nanosheets were treated with 37.5 wt% KOH. A series of tests and density functional theory calculations were conducted to explain the experimental results, which were consistent with each other. Furthermore, this method has been proven to be universal since porous WS₂ and SnS₂ nanosheets have been prepared by the same route. This study presents novel insights and reveals a new, controlled, and scalable chemical avenue for programming electrocatalysts based on MoS₂ or other layered materials.