In Situ Fabrication of Ni–Mo Bimetal Sulfide Hybrid as an Efficient Electrocatalyst for Hydrogen Evolution over a Wide pH Range

Abstract

Electrochemical water splitting to produce hydrogen bears a great commitment for future renewable energy conversion and storage. By employing an in situ chemical vapor deposition (CVD) process, we prepared a bimetal (Ni and Mo) sulfide-based hybrid nanowire (NiS<sub>2</sub>/MoS<sub>2</sub> HNW), which was composed of NiS<sub>2</sub> nanoparticles and MoS<sub>2</sub> nanoplates, and revealed that it is an efficient electrocatalyst for the hydrogen evolution reaction (HER) over a wide pH range due to the collective effects of rational morphological design and synergistic heterointerfaces. On a simple glassy carbon (GC) electrode, NiS<sub>2</sub>/MoS<sub>2</sub> HNW displays overpotentials at −10 mA cm<sup>–2</sup> catalytic current density (η<sub>10</sub>) of 204, 235, and 284 mV with small Tafel slopes of 65, 58, and 83 mV dec<sup>–1</sup> in alkaline, acidic, and neutral electrolyte, respectively, exhibiting pH-universal-efficient electrocatalytic HER performance, which is comparable to the recently reported state-of-the-art sulfide-based HER electrocatalysts. Theoretical calculations further confirm that the advantage of all-pH HER activity of NiS<sub>2</sub>/MoS<sub>2</sub> originates from the enhanced dissociation of H<sub>2</sub>O induced by the formation of lattice interfaces of NiS<sub>2</sub>–MoS<sub>2</sub> heterojunctions. This work can pave a valuable route for designing and fabricating inexpensive and high-performance electrocatalysts toward HER over a wide pH range

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