Analysis of Electrocatalytic Performance of Nanostructured MoS2 in Hydrogen Evolution Reaction

Recently, renewable and non-conventional energy production methods have been getting widespread attention. Fast research progress in establishing green energy indicates the relevance of carbon-free power production. Chemical energy stored in hydrogen molecules is considered green energy to substitute conventional energy sources. It is possible to produce hydrogen without carbon emission by water electrolysis. The action of appropriate catalysts can increase the rate of water electrolysis. Among various non-harmful and cost-effective catalysts, MoS2 nanostructures emerge as electrocatalysts in water electrolysis. This paper reviews the electrocatalytic properties of nanostructures of MoS2 by analyzing different characterization techniques used in water electrolysis, such as linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy and chronopotentiometry. This article explores the relationship between electrocatalytic characteristics and the reaction mechanism. How the reaction kinetics of electrocatalyst varies with respect to the structural changes of MoS2 nanostructures, pH of surrounding medium and longevity of catalyst are analysed here. It is found that the 1T phase of MoS2 has faster catalytic activity than the 2H phase. Similarly, among the various shapes and sizes of MoS2 nanostructures, quantum dot or monolayer structures of MoS2 and doped version of MoS2 have better catalytic activity. Acidic electrolyte shows better kinetics for releasing hydrogen than other pH conditions. Longevity, catalytic behaviour over a wide pH range, cost-effective synthesis methods and non-toxicity of MoS2 catalysts suggest its future scope as a better catalyst for commercial purposes. Electrocatalytic activity, stability, future scope and challenges of various MoS2 nanostructures are reviewed here.