Abstract
MoS2 based materials are considered the most reliable alternative catalysts for the hydrogen evolution reaction (HER), where engineering of active sites has emerged as an acceptable approach to tune their HER activity. In this approach, the dispersion of bulk MoS2 in the aqueous phase was increased with a surfactant (sodium dodecyl sulfate), which reduced the exfoliation time and enhanced the exfoliation ability to produce layered MoS2 nanosheets. During the hydrothermal treatment, the nanosheets were further scissored into small nanocrystals. Nanocrystals have attractive properties with stable dispersion and high-water solubility. Our method provides a scalable, eco-friendly, easy, and low-cost strategy for designing other HER catalysts. Such ultra-small MoS2 nanocrystals with rich Mo vacancies were used as catalysts for HER, which showed excellent electrocatalytic activity with a low overpotential (95 mV) and small Tafel slope (41 mV/dec) in 0.5M H2SO4 electrolyte. The design and synthesis of the HER catalyst in this work presents a promising path for preparing active and stable electrocatalysts to replace costly metal-based catalysts for hydrogen production.
Highlights
Renewable energy sources are similar to flying stars and are the only alternative among all energy sources
The XPS measurement results show that after hydrothermal treatment of the nanosheets, the stoichiometric ratio of Mo:S in the MoS2 nanosheets and nanocrystals continuously changed from 1:2.443 to 1:2.602, showing that a large number of Mo vacancies are generated in MoS2 after the hydrothermal treatment, which is dependent on the degree of disorder
It is difficult to distinguish which defects are produced after hydrothermal treatment because a complex defect results in a higher binding energy (BE) than d (1)-Mo+4 and i-Mo+4
Summary
Renewable energy sources are similar to flying stars and are the only alternative among all energy sources. Considerable effort has improved hydrogen production efficiency.. The advancement of platinum-free electrocatalysts (Pt) is a fundamental challenge in improving the overall efficiency of the hydrogen evolution reaction (HER), in the case of resource insufficiency and an energy crisis. The growth of MoS2 based catalysts with rich active edge sites and available electrochemical surface area is vitally important for improving the overall efficiency of the HER. Tremendous effort has been made to enhance the HER activities of MoS2 based catalysts by nanostructure engineering, defect engineering, phase engineering, and heteroatom doping to increase the number of intrinsic active sites.. The catalytic performance of defect-rich MoS2 nanostructures has been studied in depth. These findings are of great importance for improving the material properties. Several studies on the development of S vacancies in MoS2 co-catalysts have been reported; there are few reports on creating Mo-vacancy rich MoS2 co-catalysts to enhance the HER activity.
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