Investigation on the Growth Mechanism of Cu2 MoS4 Nanotube, Nanoplate and its use as a Catalyst for Hydrogen Evolution in Water

Abstract

Cu₂ MoS₄ is a ternary transition-metal sulfide that shows great potential in the field of energy conversion and storage, namely catalytic H₂ evolution in water and Li-, Na- or Mg-ion battery. In this work, we report on a growth mechanism of the single-crystalline Cu₂ MoS₄ nanotube from (NH₄ )₂ MoS₄ salt and Cu₂ O nanoparticle. By probing the nature and morphology of solid products generated in function of reaction conditions we find that the crystalline Cu(NH₄ )MoS₄ nanorod is first generated at ambient conditions. The nanorod is then converted into Cu₂ MoS₄ nanotube under hydrothermal treatment due to the Kirkendall effect or a selective etching of the Cu₂ MoS₄ core. Extending the hydrothermal treatment causes a collapse of nanotube generating Cu₂ MoS₄ nanoplate. The catalytic activities of these sulfides are investigated. The Cu₂ MoS₄ shows superior catalytic activity to that of Cu(NH₄ )MoS₄ . Catalytic performance of the former largely depends on its morphology. The nanoplate shows superior catalytic activity to the nanotube, thanks to its higher specific electrochemical surface area.

Keywords: Inorganic nanotube; Kirkendall effect; mechanism; metal chalcogenide; water splitting.