S-Vacancy Defect and Transition-Metal Atom Doping to Trigger Hydrogen Evolution of Two-Dimensional MoS₂

Abstract

Two-dimensional (2D) MoS2 is commonly used as an anode catalyst for electrochemical water splitting. However, the limited active edge sites of 2D MoS2 have hindered its electrochemical performance in electrochemical water splitting. Here, experimental outcomes and density functional theory (DFT) calculations demonstrate that the catalytic performance of inert 2D MoS2 surfaces can be triggered by doping transition-metal atoms and introducing S-vacancies. In this work, the catalytic activity of different metal-doped (Cu, Mn, and Nb) 2D MoS2 with S-vacancies shows a great difference among tested MoS2-based samples. Characterizations verify the existence of dopant ions and S-vacancies. In particular, the Cu-doped electrocatalyst exhibits a low overpotential of 197 mV at 10 mA cm–2 in an acidic solution and superior stability of less than 10 mV increase in overpotential after 12 h of continuous hydrogen production process, proving that Cu doping and introduced S-vacancies can benefit the electrochemical performance. Moreover, DFT calculations reveal that S-vacancies and the further introduction of different metal ions can alter the adsorption behavior of H atoms by changing the d-band center of the in-plane Mo site neighboring the doped heteroatom atoms and S-vacancy sites, which explains well the superior performance of Cu-doped 2D MoS2.

Electric-Field-Assisted Synthesis of Cu/MoS2 Nanostructures for Efficient Hydrogen Evolution Reaction

“…Furthermore, the high hydrogen evolution reaction activity of 10-CMS is comparable with many previously reported MSbased CMS/NF electrocatalysts, as shown in Table 1. Ag-Ag2S/MoS2 H2SO4 150 Microwave-assisted technique [12] Etched MoS2 H2SO4 316 One-step microwave-assisted method [7] MoS2 Quantum Dot H2SO4 190 Hydrothermal Method [22] MoS2NTs array H2SO4 296 Electrophoretic Deposition [8] Cu-MoS2-SV H2SO4 197 Chemical Etching Method [23] Cu9S5@MoS2 KOH 146 Chemical Vapor Deposition (CVD) [24] In electrochemistry, the reaction kinetics of electrochemical reactions are described by a Tafel slope. The sensitive response of the current to overpotential can be illustrated by plotting the logarithm of the current density (log(j)) against η [17].…”

Introduction of MoS2–FeS2 with an S-Vacancy Defect as an Efficient Bifunctional Electrocatalyst for Hydrogen Evolution Reaction and Ferrocyanide and Iodide Oxidation Reactions

“…Electrolytic water splitting stands as a popular method for hydrogen production due to its simplicity, environmental friendliness, and high product purity. − However, the process, involving the hydrogen evolution reaction (HER) at the cathode and an oxygen evolution reaction (OER) at the anode, , typically operates at voltages exceeding the theoretical minimum , due to the sluggishness of the anodic OER. This inefficiency contributes to increased energy consumption and surplus oxygen production. − …”