Facile Synthesis of Molybdenum Diselenide Layers for High-Performance Hydrogen Evolution Electrocatalysts

A cost-effective solution-based synthesis route to grow MoSe₂ thin films with vertically aligned atomic layers, thereby maximally exposing the edge sites on the film surface as well as enhancing charge transport to the electrode, is demonstrated for hydrogen evolution reaction. The surface morphologies of thin films are investigated by scanning electron microscopy and atomic force microscopy, and transmission electron microscopy analyses confirm the formation of the vertically aligned layered structure of MoSe₂ in those films, with supporting evidences obtained by Raman. Additionally, their optical and compositional properties are investigated by photoluminescence and X-ray photoelectron spectroscopy, and their electrical properties are evaluated using bottom-gate field-effect transistors. The resultant pristine MoSe₂ thin film exhibited low overpotential of 88 mV (at 10 mA·cm^-2) and a noticeably high exchange current density of 0.845 mA·cm^-2 with excellent stability, which is superior to most of other reported MoS₂ or MoSe₂-based catalysts, even without any other strategies such as doping, phase transformation, and integration with other materials.