MoS₂ Nanosheets on MoNi₄/MoO₂ Nanorods for Hydrogen Evolution

Abstract

Active electrocatalytic electrodes have been long searched as potential alternatives to platinum-free electrodes for the hydrogen evolution reaction (HER). Here, we report the development of a hybrid nanostructure of two-dimensional (2D) MoS2 nanosheets grown on MoNi4/MoO2 nanorods as a synergistic nanostructure for the hydrogen evolution reaction. The nanostructure is unique as it is composed of vertically grown few-layer atomically thin MoS2 nanosheets supported on MoNi4/MoO2 nanorods with an extraordinarily high surface area. Structural and morphological characterizations illustrate that the 2D MoS2 nanosheets were uniformly coated on the MoNi4/MoO2 nanorods via a facile hydrothermal process. The distinct phase formation, surface compositions, and bonding states confirm the structural integrity and compositional homogeneity between MoS2 and MoNi4/MoO2 nanorods in the synergistic nanostructures. Electrochemical characterizations showed that the MoS2:MoNi4/MoO2 electrodes exhibited a narrower Tafel slope (67 mV dec–1) and a lower overpotential (η10 = 155.6 mV) compared to the pristine MoS2, thereby accelerating hydrogen evolution reactions in an alkaline medium. Also, the synergistic nanostructure-based electrode showed faster charge transport for the HER compared to pristine 2D MoS2 while exhibiting a higher number of the catalytically active sites for the accelerated charge transfer process. The synergistic MoS2:MoNi4/MoO2 nanostructure electrode shows more than 8 h stability with enhanced HER performance.

Tungsten–Nickel Alloy Boosts Alkaline Hydrogen Evolution Reaction

“…Besides, the NiWO 4 precursors also showed a large overpotential value (265 mV), implying the vital role of the W–Ni electronic interactions in the synergistic effect of the enhanced alkaline HER activity. Encouragingly, the WNi 4 @W–WO 2 sample exhibited a markedly high alkaline HER activity with a low overpotential at 10 mA/cm 2 (η 10 = 83 mV), which is much more superior than those of previously reported alloy catalysts, − and even being competitive to the commercial Pt/C catalyst (η 10 = 48 mV) (Figure a,c). Besides, in order to eliminate the influence of the substrate, the polarization curves of WNi 4 @W–WO 2 powder loading onto glassy carbon electrode (GCE) and carbon film were also collected in 1 M KOH electrolyte, respectively (electrode fabrication seen in experiment details).…”

Electron Density Modulation of MoO2/Ni to Produce Superior Hydrogen Evolution and Oxidation Activities

“…The high-resolution Ni 2p XPS spectrum (Figure S6b) shows three sets of double peaks. The peaks at approximately 852.88 and 869.99 eV match with the Ni 2p 3/2 and Ni 2p 1/2 peaks of Ni 0 , and the peaks at 861.78 and 879.99 eV correspond to the Ni 2p 3/2 and Ni 2p 1/2 peaks of Ni 2+ , while the peaks at 856.19 and 873.89 eV are satellite peaks. − Meanwhile, the high-resolution Mo 3d XPS spectrum of MoO 2 /Ni (Figure S6c) can be deconvoluted to three sets of double peaks from Mo 3+ , Mo 4+ , and Mo 6+ . The corresponding 3d 5/2 peaks are located at 229.38, 230.70, and 232.54 eV, and the 3d 3/2 peaks are situated at 232.54, 234.05, and 235.63 eV, respectively. − In addition, the peaks at approximately 530.65 and 532.02 eV are attributed to the metal–O and O–H bond of O 1s in MoO 2 /Ni (Figure S6d).…”

Recent advances in MoS2-based materials for electrocatalysis

“…(2) The unique structure of these carriers enables H + ions to have access to the active sites of MoS 2 nanomaterials through the electrolyte. 99,110,111 Carbonaceous materials such as graphene, carbon nanotubes, and carbon nanofibers have been proven to be effective matrices that can endow MoS 2 with specific shapes, expand the interlayer spacing, and increase the conductivity, etc. Various MoS 2 /carbon nanohybrids with boosted HER performances have been reported in recent works.…”