Electrodeposited Transition Metal Dichalcogenides for Use in Hydrogen Evolution Electrocatalysts

Abstract

Hydrogen is a promising alternative to gasoline due to its higher energy density and ability to burn cleanly only producing H2O as a by-product. Electrolytic water splitting is an effective technique for generating molecular hydrogen. However, for hydrogen to be a viable alternative energy source to be produced from water electrolysis, affordable and durable electrocatalysts need to be developed to replace platinum. Transition metal dichalcogenides (TMDs) are a promising alternative since they are abundant, inexpensive, and have a tunable structure. There are various ways to produce TMD films including chemical and mechanical exfoliation, chemical vapor deposition (CVD), and electrodeposition. Exfoliation and CVD techniques often require a transfer of TMDs from the growth substrate to an electrode, which introduces impurities and possible defects to the film. Electrodeposition, however, provides a way to produce TMDs directly onto the electrode with excellent surface coverage. This work uses electrodeposition to produce TMD and TMD bilayer electrodes using sequential electrodeposition for electrocatalytic hydrogen evolution reaction (HER). The results presented include cost-effective deposition techniques along with enhanced proton reduction activity for the sequentially deposited bilayer TMD structure consisting of MoS2 and MoSe2, which suggests the electron transfer kinetics from the conductive glass substrate to the top-layer is enhanced with a MoS2 layer. Furthermore, the bilayer structures synthesized by sequential deposition are characterized via XPS, XPS depth-profiling, and SEM-EDS for enhanced understanding of the fabricated structure.