MoS₂ Nanoflowers Grown on Plasma‐Induced W‐Anchored Graphene for Efficient and Stable H₂ Production Through Seawater Electrolysis

Abstract

Herein, it is found that 3D transition metal dichalcogenide (TMD)—MoS2 nanoflowers—grown on 2D tungsten oxide‐anchored graphene nanosheets (MoS2@W‐G) functions as a superior catalyst for the hydrogen evolution reaction (HER) under both acidic and alkaline conditions. The optimized weight ratio of MoS2@W‐G (MoS2:W‐G/1.5:1) in 0.5 M H2SO4 achieves a low overpotential of 78 mV at 10 mA cm–2, a small Tafel slope of 48 mV dec–1, and a high exchange current density (0.321 mA cm⁻2). Furthermore, the same MoS2@W‐G composite exhibits stable HER performance when using real seawater, with Faradaic efficiencies of 96 and 94% in acidic and alkaline media, respectively. Density functional theory calculations based on the hybrid MoS2@W‐G structure model confirm that suitable hybridization of 3D MoS2 and 2D W‐G nanosheets can lower the hydrogen adsorption: Gibbs free energy (∆GH*) from 1.89 eV for MoS2 to –0.13 eV for the MoS2@W‐G composite. The excellent HER activity of the 3D/2D hybridized MoS2@W‐G composite arises from abundance of active heterostructure interfaces, optimizing the electrical configuration, thereby accelerating the adsorption and dissociation of H2O. These findings suggest a new approach for the rational development of alternative 3D/2D TMD/graphene electrocatalysts for HER applications using seawater.

Recent Advances in Doping Strategies to Improve Electrocatalytic Hydrogen Evolution Performance of Molybdenum Disulfide

“…111,112 Both continuous cyclic voltammetry scanning and timing amperage/timing potential methods are commonly employed to evaluate the long-term stability of electrocatalysts. 113 The timing amperage method, which measures changes in current and reaction time at a specific potential, can also assess potential changes through chronoamperometry. Currently, the standard is to maintain a current density not below 10 mA cm −2 and ensuring a measurement duration of no less than 10 h. Another prevalent method for studying stability involves comparing LSV or CV curves before and after at least 5000 electrochemical reactions.…”

“…Given that most research on electrocatalytic hydrogen production now occurs in strong acid or base solutions, high stability is essential for most catalysts. , Both continuous cyclic voltammetry scanning and timing amperage/timing potential methods are commonly employed to evaluate the long-term stability of electrocatalysts . The timing amperage method, which measures changes in current and reaction time at a specific potential, can also assess potential changes through chronoamperometry.…”

Defect and interface/surface engineering synergistically modulated electron transfer and nonlinear absorption properties in MoX2 (X = Se, S, Te)@ZnO heterojunction

“…7 In addition, it is one of the most promising nonlinear optical (NLO) materials because of its ability to adjust optical and electronic properties in a layer-by-layer manner and its excellent NLO properties. Based on the rapid development of preparation technology and practical applications of MoX 2 materials, researchers are exploring the potential of these materials in photodetectors, 8 field-effect transistors, 9 sensors, 10 photocatalysis, 11,12 electrocatalysis, 13–15 and photovoltaics. 16 Due to their novel self-assembly properties, such as large modulation depth, large NLO coefficient, large third-order NLO polarization, and adjustable band gap, 17 MoX 2 materials are promising candidates as a saturable absorber of lock films.…”

In Situ Phase Separation-Induced Self-Healing Catalyst for Efficient Direct Seawater Electrolysis

“…Although non-noble metal-based catalysts (such as metal oxide, 15 metal hydroxide, 16 and sulfide 17 ) capable of performing at 500−800 mA cm −2 in an alkaline seawater environment (with the addition of 1 M KOH) at 1.7−1.8 V have been reported, natural seawater electrolysis generally requires over 2.0 V to achieve a current density of over 100 mA cm −2 . 18,19 Furthermore, the competition between the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) can lead to a reduction in the current density of the electrolytic process and induce chlorine corrosion of the electrode. 15,20 Moreover, the formation of cationic insoluble precipitates on the surface of the electrode can result in a significant decay in the performance of the catalyst and even lead to deactivation.…”

“…Typically, for direct seawater electrolysis, the addition of strong alkalis (US$1320/MT, caustic potash) to seawater precedes electrolysis; this inevitably complicates the operational procedure and increases its cost. , More importantly, seawater electrolysis is less efficient than conventional alkaline electrolysis. Although non-noble metal-based catalysts (such as metal oxide, metal hydroxide, and sulfide) capable of performing at 500–800 mA cm –2 in an alkaline seawater environment (with the addition of 1 M KOH) at 1.7–1.8 V have been reported, natural seawater electrolysis generally requires over 2.0 V to achieve a current density of over 100 mA cm –2 . , Furthermore, the competition between the chlorine evolution reaction (CER) and oxygen evolution reaction (OER) can lead to a reduction in the current density of the electrolytic process and induce chlorine corrosion of the electrode. , Moreover, the formation of cationic insoluble precipitates on the surface of the electrode can result in a significant decay in the performance of the catalyst and even lead to deactivation. Compared with the pH of the original seawater during electrolysis, the pH values near the surface of the electrode may range from 5 to 9 pH units.…”