Abstract
Widely used precious metal (i.e., Pt, or Pd) electrocatalysts need to be replaced with other cost-effective and earth-abundant materials for economical water splitting applications. Recently, two-dimensional (2D) transition metal dichalcogenides (MoS2, VS2, WS2, etc.) have emerged as ideal electrocatalysts for the hydrogen evolution reaction (HER) due to their tunable physicochemical properties and rich catalytic active sites. In this regard, we propose a strategy to achieve improved HER performance of VS2 by fabricating a hybrid material with transition metal (Zn and Cd)-based sulfides. A facile hydrothermal approach is employed to prepare a VS2/ZnS/CdS hybrid catalyst that exhibits remarkable electrocatalytic performance for the HER in acidic media with a small overpotential of 86 mV at 10 mA/cm2 and a Tafel slope of 74.4 mV/dec. This inferred the Volmer–Heyrovsky mechanism with electrochemical desorption of hydrogen as the rate-limiting step. High performance is attributed to the abundance of catalytically active sites and the synergistic interactions between the materials. Theoretical calculations reveal that the VS2/ZnS/CdS hybrid shows favorable HER activity owing to its low hydrogen adsorption free energy of about 0.35 eV. We believe that this work on designing 2D VS2/ZnS/CdS will offer a new pathway to discover an efficient H2 generation electrocatalyst.
Highlights
Increasing global energy demands and simultaneous shrinkage of conventional fuel sources stimulated enormous research focus on the development of technologies for sustainable energy conversion and storage
We have developed a simple and effective strategy to fabricate the VS2/zinc sulfide (ZnS)/Cadmium sulfide (CdS) hybrid structures with excellent electrocatalytic hydrogen evolution reaction (HER) properties
From the first-principles study, we found that VS2/ZnS/CdS is more favorable in HER activity as compared to pristine VS2
Summary
Increasing global energy demands and simultaneous shrinkage of conventional fuel sources stimulated enormous research focus on the development of technologies for sustainable energy conversion and storage. Among the various non-precious metal-based electrocatalysts, transition metal sulfides have emerged as the superior HER electrocatalysts in recent years.7 The advantageous properties, such as good conductivity, low cost, less environmental impact, and considerable catalytic activity toward the electrochemical HER, make them promising candidates. VS2 exhibits a small bandgap partly filled at the Fermi level, attractive metallic behavior with high electrical conductivity, high specific surface area, and unique mechanical properties.10 Due to these several fascinating properties, VS2 has become a superior candidate for facilitating various electrochemical applications, including supercapacitors, batteries, and electrocatalytic water splitting.. Theoretical calculations reveal that the VS2/ZnS/CdS hybrid structure is favorable in HER activity due to its low hydrogen adsorption free energy, which is about 0.35 eV These fruitful outcomes evidence that the fabrication of optimized hybrid nanostructures is a promising strategy to enhance the catalytic performance of VS2 material. These precious metal-free and highly active catalysts for the HER enable prospective opportunities for 2D materials in industrial applications
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