Synergistic Effects of Tungsten Doping and Sulfur Vacancies in MoS₂ on Enhancement of Hydrogen Evolution

Abstract

Molybdenum sulfide (MoS2) has extensively attracted attention as a promising nonprecious metal catalyst for the electrochemical hydrogen evolution reaction (HER). Nevertheless, synergistically enhancing the intrinsic conductivity and active sites of MoS2 is the pivotal challenge to build up its hydrogen production performance. Herein, a facile ionic liquid-assisted hydrothermal and subsequent annealing treatment strategy is first reported to synthesize W-doped MoS2 nanosheets supported on carbon cloth (Mo1‑x W x S y /CC). The experimental results prove that the substitutional W doping can effectively activate the catalytic activity of the inert basal plane of MoS2 due to the generation of sulfur vacancies. Density functional theory calculations further confirm that W doping and S vacancies reduce the band gap of MoS2 and promote the adsorption of H atoms, thereby greatly improving the HER performance. The synergistic effects of W doping and S vacancies endow this material remarkable HER performance with a low Tafel slope of 49.3 mV dec–1 and an overpotenial of 165 mV for 10 mA cm–2 in 0.5 M H2SO4 solution. In short, our new strategy provides a simple and efficient pathway to synthesize Mo1‑x W x S y /CC, and it can be applied to the design of other materials possessing multifarious merits.

Mo‐Doped Sulfur‐Vacancy‐Rich V1.11S2 Nanosheets for Efficient Hydrogen Evolution

“…To further confirm the successful introduction of S vacancies, an electron paramagnetic resonance (EPR) spectroscopy test was performed, where higher intensities indicate more unpaired electrons and vacancies. As shown in Figure 2f, the EPR spectroscopy provides a typical signal of sulfur vacancies at g=2.003 in 0.5Mo–V 1.11 S 2 and 0.5Mo–V 1.11 S 2‐x while the intensity of 0.5Mo–V 1.11 S 2 is significantly weaker and narrower than that of 0.5Mo–V 1.11 S 2‐x , which confirming that there existed more defects in the 0.5Mo–V 1.11 S 2‐x samples [51–52] . Therefore, based on the above results, we can definitely conclude that Mo‐doped V 1.11 S 2 catalysts with abundant sulfur vacancies were successfully synthesized.…”

MoWS2 nanosheets incorporated nanocarbons for high-energy-density pseudocapacitive negatrode material and hydrogen evolution reaction

“…11 In addition to this, many hierarchal systems have been subjected to electrochemical measurements. [19][20][21][22][23][24][25][26] However, to our knowledge, MoWS 2 is not being used as an electrode for supercapacitors which can beexplored. Herein, to the best of our knowledge, we have demonstrated MoWS 2 and its nanocarbon (MWCNT and rGO)-incorporating hybrids as bifunctional, i.e., electrocatalyst and negatrode, materials for both energy conversion and storage applications for the very rst time.…”

Simple Ball‐Milled Molybdenum Sulfide Nanosheets for Effective Interface Passivation with Self‐Repairing Function to Attain High‐Performance Perovskite Solar Cells

“…When the commercial MoS 2 powders were annealed at 100 °C, seven new Raman modes of 198, 222, 352, 486, 516, 815, and 830 cm −1 appear, but two Raman modes of 83 and 95 cm −1 disappear, which indicate that the annealed process could repair the surface defects to avoid activating Mo atoms exposed on the surface and obtain a more ordered Mo—S bond. [ 27 ] Thus, the frequency difference between A 1g and E 1 2g increases to ≈27 cm −1 (Figure 1f). Except for above seven new Raman peaks, the intensity of the remaining peaks decreases with some degree.…”

“…The catalytic activity of inorganic metal sulfide can affect the stability of the heterojunction interface and is characterized through the hydrogen evolution reaction that correlated with the number of exposed edge sites with local stoichiometry and a physical and electronic structure. [ 28 ] Some investigations have confirmed that the catalytically active sites of MoS 2 are confined to its edges, [ 27 ] especially at the Mo edge active sites and unsaturated S vacancy sites. [ 29 ] MoS 2 nanosheets with smaller size and higher dispersion could provide much more exposed active edges.…”