Recent advances in metallic transition metal dichalcogenides as electrocatalysts for hydrogen evolution reaction

Recent Advances in Defect-Engineered Transition Metal Dichalcogenides for Enhanced Electrocatalytic Hydrogen Evolution: Perfecting Imperfections

“…= b j j log 0 (8) where η is the overpotential, j is the current density, j 0 is the exchange current density, and b is the Tafel slope in the unit of mV/dec.…”

“…Specifically, hydrogen is an excellent fuel since it possesses a high energy density of 142 MJ/kg and is versatile use because it can be converted back into electricity in a fuel cell or can be mixed with natural gas and combusted for municipal cooking and heating. 8 More importantly, hydrogen produces only the environmentally benign water when it is oxidized to release its stored energy. 9,10 Currently, hydrogen is conventionally produced by steammethane reforming (gray hydrogen), which is an energyintensive process that produces CO 2 as a byproduct.…”

2D Transition Metal Dichalcogenides‐Based Electrocatalysts for Hydrogen Evolution Reaction

“…Numerous parameters are important, such as atomic level thickness plane, high surface area, edge effects, topological effects, short ion diffusion distance, alleviated restacking, efficient charge transfer, and abundant active sites, which could be a diverse advantage in favor of HER. [40,42,[154][155][156][157]43,44,46,47,89,90,152,153] Bulk 2D based materials can be straightforwardly exfoliated into atomically thin layer sheet, including single and/or double layer, owing to the presence of weak van der Waals force between the layers, which can be easily separated with minimum efforts depending on their different physicochemical properties such as density, conductivity, corrosion resistance, melting point, and chemical stability. [12,40,154,155,157,[42][43][44]47,87,89,90,152] In case of transition metal based chalcogen materials, the transition metal atoms and chalcogen atoms would be exposed in their top position of the materials where electrolyte can access the active surface easily.…”

“…[267] The most important physicochemical properties of 2D transition metal chalcogenides have been benefited by their activated basal plane, edges, strain, controlled morphology, and monolayers, which are helping them to build excellent electrocatalytic materials for HER. [42][43][44]113,268] Generally, metal chalcogenides have been fabricated through different synthetic strategies including CVD, hydrothermal colloidal, solid states, etc., which have been discussed in earlier sections and shown in Table 1. 2D metal chalcogenide-based materials in various forms are very important nanostructures for the electrocatalytic performances of hydrogen evolution reactions toward a greener environment.…”

“…In addition, surface modification of the 2D structure is an effective strategy to obtain high performance in HER, and 2D materials have maximized exposed surfaces in form of basal planes. [28,[40][41][42][43][44][45][46] Because of the distinctive properties of the 2D nanomaterials along with transition metal carbide and transition metal chalcogenides, numerous research efforts have been made to create effective 2D nanostructures toward electrocatalytic HER, mainly based on the fundamental mechanisms outlined in Scheme 1. Different approaches have been adopted including enhancement of electronic conductivity, increase of the density of active site of the catalyst and engineering of the catalyst at nanoscale level.…”