Defects Enhance the Electrocatalytic Hydrogen Evolution Properties of MoS₂‐based Materials

Abstract

MoS 2 have recently emerged as alternatives to noble metals as electrocatalysts for the hydrogen evolution reaction (HER) owing to their abundance and low cost. Considering the shortcomings of MoS 2 , including insufficient active sites, inert basal plane, and poor conductivity, the electrocatalytic hydrogen evolution properties of MoS 2 can be improved in three ways: activating the inert basal plane to improve intrinsic activity, increasing active edge sites, and improving the conductivity. Defects can adjust the surface electronic structure of the crystal to bring the hydrogen adsorption free energy closer to zero. Therefore, current research has mainly used S-vacancies to activate the inert basal surface of MoS 2 ; used edge defects to increase the number of active sites; and used defective conductive carbon supports to improve the conductivity of MoS 2-based catalysts. This review introduces researches on improving the performance of MoS 2 for HER by considering the purpose, characterization, and preparation of defects.

Interfacial electronic structure engineering on molybdenum sulfide for robust dual-pH hydrogen evolution

“…Among these candidates, MoS 2 , a typical layered 2D TMDCs formed by Van der Waals interaction and stacking of S–Mo–S layers, attracts extensive interests with its adjustable bandgap, unique band structure, high energy-conversion efficiency, and earth abundance 23 – 25 . However, the electrocatalytic activity of MoS 2 is closely associated with its surface electric structure 26 – 36 , many researchers have focused on adjusting the electronic structure of the MoS 2 surface to promote electrocatalytic activity, such as surface engineering 26 , doping 27 , single-atom anchoring 28 , phase structure 29 – 33 , interface active site 34 , 35 , and defect 36 . Interestingly, two main phases of MoS 2 were widely justified: 2H and 1T phases 29 .…”

Synergetic contribution of enriched selenium vacancies and out-of-plane ferroelectric polarization in AB-stacked MoSe2 nanosheets as efficient piezocatalysts for TC degradation

“…22 This exfoliation method is driven by the strong etching and oxidative ability of chemical reagents (such as H 2 O 2 , HNO 3 , KOH and NaClO), which not only break the weak van der Waals forces between the layers, but also induce the formation of plentiful chalcogen vacancies. [23][24][25] Vacancy defects not only affect the surface electronic structure, but also change the local electrical polarization of MoSe 2 . 26 Thus, it is expected that chemical reagent-exfoliated MoSe 2 will exhibit higher piezocatalytic activity towards the degradation of pollutants.…”

Impact of Surface Defects on LaNiO3 Perovskite Electrocatalysts for the Oxygen Evolution Reaction

“…The half-circle diameter represents the charge transfer resistance (R ct ) at the interface between electrolyte and electrocatalyst, and was significantly smaller for red-LNO-700 (151 Ω) than LNO-700 (246 Ω) or LNO-900 (260 Ω), suggesting faster interfacial charge transfer rate for the former, attributed to surface defects whose presence can tune surface electronic states and increase conductivity. [35] The electrochemically active surface area (ECSA) of LNO materials was evaluated by measuring their double-layer capacitances (C dl ) in non-Faradaic potential regions. Cyclic voltammetry was performed at 0.87-0.97 V (versus RHE) at scan rates spanning 100-600 mV s À 1 (Figure S7).…”