Unique hybrid Ni2P/MoO2@MoS2 nanomaterials as bifunctional non-noble-metal electro-catalysts for water splitting

We successfully synthesized a novel electro-catalyst with a unique structure of Ni2P nanoparticles decorating the surface of MoO2@MoS2 sub-microwires on titanium foil (denote as NiMoO-SP/Ti) via a facile temperature-programmed sulfuration-phosphorization from its nickel molybdate precursor. The metallic MoO2 core facilitates electron transfer, and the interfaces between MoS2 nanosheets and Ni2P nanoparticles enhance catalytic activity both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Due to this unique structure, the obtained NiMoO-SP/Ti showed an enhanced OER performance in alkaline solution with a small Tafel slope of 85 mV dec(-1) and a low overpotential of 280 and 360 mV to achieve 10 and 100 mA cm(-2) in 1.0 M KOH, respectively. The catalyst also exhibited an excellent stability in 1.0 M KOH, with just 12 mV shift after electrolysis at 10 mA cm(-2) for 16 h and 27 mV shift after electrolysis at 20 mA cm(-2) for another 24 h. In addition, the NiMoO-SP/Ti also displayed high catalytic properties towards HER with a small Tafel slope of 77 mV dec(-1) and a low overpotential of 159 mV to obtain 10 mA cm(-2) in 1.0 M KOH. After electrolysis at -10 mA cm(-2) for 40 h, the overpotential increased by just 25 mV, which demonstrated its high stability for HER in 1.0 M KOH. This work provides an effective route to designing a high-performance catalyst with a favorable structure for the development of electro-catalysts for water splitting.