Research Fellow, Griffith University
Transition metal sulfide electrocatalyst for energy conversion applications
Efficient and one-step synthetic route for preparing transition metal-based electrocatalysts is significantly important for many energy conversion applications. Generally, most of the electrocatalysts requires conducting substrates as a support (graphene, carbon, carbon nanotube etc.) to improve the electronic conductivity and expedite their applications in electrocatalysis . Here, we report a facile and one-step  modified molten-salt  calcination method to prepare cobalt pentlandite (Co9S8) and heazlewoodite (Ni3S2) nanoparticles (NPs) supported on carbon nanosheet (CNS). The detailed reaction mechanism for these syntheses was systematically investigated using TG/DSC-MS analysis and a comprehensive reaction mechanism was proposed. Both of these synthesised materials were tested as electrocatalysts for oxygen evolution reactions (OERs) in 1.0 M KOH electrolyte. The Co9S8 and Ni3S2 exhibited the overpotential of 294 and 298 mV at a current density of 10 mA cm-2, respectively, which are better than benchmark RuO2 and most other cobalt or nickel based catalysts reported to date. More importantly, we were able to synthesise few-layered graphitic carbon (~5 atomic layers) encapsulated Ni3S2 (Ni3S2@C) NPs that provided superb electrocatalytic stability in OER application. Therefore, the synthetic strategy introduced in this work may benefit further exploration of other highly efficient and stable electrocatalysts for energy conversion and storage applications.