Vanadium sulfides interwoven nanoflowers based on in-situ sulfurization of vanadium oxides octahedron on nickel foam for efficient hydrogen evolution

Highlights: • VS interwoven nanoflowers supported on nickel foam (VO-S/NF) were synthesized. • VO-S/NF including vs and Ni₃S₂ can provide interface effect between vs and Ni₃S₂. • VO-S/NF has the high HER activity and structural stability for HER performances. • It may be a new way to design transition metal sulfides hybrid electrocatalysts. - Abstract: Novel vanadium sulfides interwoven nanoflowers supported on nickel foam (VO-S/NF) has been synthesized through a facile two-step access. Firstly, octahedron-structured vanadium oxides as precursor were anchored on the surface of NF (VO/NF) by a hydrothermal process. Secondly, in-situ sulfurization in H₂S gas has been applied to prepare VO-S/NF. XRD shows that VO-S/NF sample is composed of mixture phases including VS and Ni₃S₂, implying the interface effect between VS and Ni₃S₂. SEM images demonstrate that octahedron-structured VO from VO/NF changed to VO-S interwoven nanoflowers on VO-S/NF, which are composed of vertical interwoven nanosheets. It can enlarge surface area to expose abundant active sites and facilitate mass and charge transportation. The electrochemical measurements display the enhanced HER activity of VO-S/NF requiring an overpotential of 165 mV to deliver 10 mA cm⁻², which may be ascribed to the novel structure of VS interwoven nanosheets and the synergistic effect between VS and Ni₃S₂. Furthermore, VO-S/NF remains high HER activity for at least 10 h with excellent structural stability confirmed by post-HER characterization such as XRD, SEM and XPS. Therefore, it may provide a new way to design multiple transition metal sulfides-based electrocatalysts with unique nanostructure as well as interface effect for HER in alkaline.