Engineering MoS2 nanostructures from various MoO3 precursors towards hydrogen evolution reaction

Abstract

MoS₂-based nanomaterials are considered promising effective electrocatalysts to replace precious metal catalysts for hydrogen evolution reaction. However, understanding the effect of MoO₂ in MoS₂-based catalysts for hydrogen evolution reaction is ambiguous. In this paper, MoS₂ nanoflowers of 210–430 nm in diameter were hydrothermally synthesized by the reduction of α-MoO₃ particles with KSCN in a hydrochloric acid medium. Similarly, MoO₂–MoS₂-B nanoflowers and MoO₂–MoS₂-R nanoflowers were fabricated using α-MoO₃ nanobelts and h-MoO₃ microrods as Mo sources, respectively. Systematic studies on synthetic parameters verified that the formation of MoS₂ nanoflowers is favored with high acidity, low MoO₃/KSCN ratio and high temperature. The resultant nanoflowers served as electrocatalysts to drive hydrogen evolution in acidic solution. The MoS₂ nanoflowers showed a relatively higher activity with a potential of 256 mV at 10 mA cm⁻² compared to MoO₂–MoS₂-B nanoflowers (283 mV) and MoO₂–MoS₂-R nanoflowers (305 mV). Furthermore, MoS₂ nanoflower catalysts maintained high stability after 1000 cycles and long-term durability for 5 h. The high catalytic activity could be ascribed to the large exposure of the Mo–S species and small amounts of Mo–O species on the MoS₂-based catalyst surface.