FeV3O8/MoS2 nanostructure heterojunctions as a highly effective electrocatalyst for hydrogen evolution

Abstract

Great efforts have been made to explore efficient, stable and resource-rich non-noble metal electrocatalysts instead of noble metal electrocatalysts for the hydrogen evolution reaction (HER). As typical 2D transition-metal dichalcogenide (TMD) electrocatalysts, the application of MoS₂ in water splitting is restricted due to its poor conductivity and having lots of inactive sites at the edge. The preparation of a MoS₂ composite heterojunction was deemed to be a promising way to enhance the electrocatalytic performance. Herein, FeV₃O₈/MoS₂ (FVO/MS) heterostructures were in situ constructed by synthesizing graphene-like MoS₂ nanosheets on FeV₃O₈ nanorods. The phase structure, morphology and chemical composition of the samples were analyzed by XRD, FESEM, XPS, HRTEM and Raman spectra, respectively; these results confirmed that FVO/MS were successfully coupled together and formed a clear and intimate interface. According to the electrochemical tests under acid conditions (0.5 M H₂SO₄), the FVO₄₀-MS heterostructure presents an impressive HER catalytic ability with a lower overpotential of 160 mV (at 10 mA cm⁻²) and a smaller Tafel slope of 53 mV dec⁻¹ in contrast to pure MoS₂. Combining all the test results, the improved HER performance of FVO/MS catalysts was found to be derived from the synergistic effect between FeV₃O₈ and MoS₂, the increased active sites at the edge of the heterojunction, the enhanced conductivity and the larger BET surface area. This work may provide a valuable way of developing MoS₂-based electrocatalysts for the HER in acid systems.