Defect Engineering in Metastable Phases of Transition‐Metal Dichalcogenides for Electrochemical Applications

Abstract

Metastable metallic phases of transition-metal dichalcogenide (TMD) nanomaterials have displayed excellent performance and emerged as promising candidates for sustainable energy sources low-cost storage and conversion because of their two-dimensional (2D) layered structures and extraordinary physicochemical properties. In order to broaden the range of potential applications, defect engineering is applied to the metastable phases of TMDs for further improvement of their catalytic and electronic properties. According to some recent studies, effective introduction of defects without perturbing the interior conductivity contributes to the development of metastable TMDs. This review provides deep insights into recent progress in electrochemistry using defect engineering in the metastable phases of TMDs. After introducing the structures of metastable phases and methods for defect construction, significant developments in catalysis and energy storage applications are discussed to elucidate structure-function relationships. Key challenges and future directions for defect engineering in the metastable phases of TMDs are also highlighted in the conclusions.

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

“…Vertically oriented MoS 2 nanosheets can also be obtained, and [166] Copyright 2012, Nature Publishing Group) b) schematic illustration of the heterostructure combining single-layer fractal-shaped MoS 2 and single-layer graphene and the HER performances of the fractal-shaped single-layer MoS 2 (sample c) and Pt foil measured in this work, including two important parameters, overpotential η (mV vs. RHE) when j = −10 mA cm −2 and Tafel slope (Reproduced with permission. [167] Copyright 2018, Elsevier). c) Schematic illustration of the preparation process and microstructure and polarization curves Reproduced with permission.…”

“…The most important aspects that affect HER performance when it comes to defect engineering are the different phases of catalytic site and their intensities in the basal planes or surfaces, including terraces, low coordinated atoms, different size of pores, corner atoms, and kinks, these properties can make the basal plane with more catalytically active edges, the quantity of the defects in basal planes may also have an influence on the catalytic performances based TMDs nanoscale materials. [37,167,168,190,[194][195][196] Currently, plasma-based approach has drawn a widespread attention to increase the catalytic activity of inactive basal plane of the different TMDs. For example, Chen et al fabricated a highly dense porous at atomic scale of "2D" TaS 2 materials to enhanced the electrocatalytic activity [52] (Figure 8a).…”

“…[ 163–166 ] Owing to their exposed edges as an active site in their inert basal plane, it is highly important to control the way the edge sites are exposed and to be able to selectively create exposed edges and defect engineering which have been involved to modify the HER activity. [ 167–169 ]…”

“…a) Synthesis procedure and structural model for mesoporous MoS 2 with a double-gyroid (DG) morphology and Ratios of surface area, density of active sites per surface area and total HER activity of the various double-gyroid MoS 2 films versus the nanowires (Reproduced with permission [166]. Copyright 2012, Nature Publishing Group) b) schematic illustration of the heterostructure combining single-layer fractal-shaped MoS 2 and single-layer graphene and the HER performances of the fractal-shaped single-layer MoS 2 (sample c) and Pt foil measured in this work, including two important parameters, overpotential η (mV vs. RHE) when j = −10 mA cm −2 and Tafel slope (Reproduced with permission [167]. Copyright 2018, Elsevier).…”

Recent advances in solution assisted synthesis of transition metal chalcogenides for photo-electrocatalytic hydrogen evolution

“…Since an excess of defect generation may result in cracking of the crystal planes, cracking exposes the active sites, increasing the specific surface area, which consequently increases the hydrogen evolution activity. 162,169 Additionally, defect generation also improves the separation of charge carriers. 170 Fig.…”