Preparation and characterization of bifunctional 1T-2H MoS₂-S_v/CuS catalyst for electrocatalytic hydrogen and oxygen evolution reaction

The two-dimensional transition-metal disulfide compounds, such as molybdenum disulfide (MoS₂), have been identified as highly promising candidates for electrocatalytic water splitting. The performance of MoS₂ in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is still inferior to that of precious metals. The rational design of the electrocatalyst structure is crucial for achieving bifunctional HER/OER reactions. Herein, the 1T-2H molybdenum sulphide with sulfur vacancy/copper sulphide (1T-2H MoS₂-S_v/CuS) catalyst with dual functions of HER and OER was synthesized via a one-step hydrothermal method, utilizing prepared copper(I) oxide (Cu₂O) as the precursor. The surface of MoS₂ substrate generates sulfur vacancies (S_v), which enriches the active site. These S_v to the benefit of MoS₂ phase transition from a stable 2H phase to a more catalytically active 1T phase. The synergistic effect of 1T MoS₂ and copper sulphide (CuS) promotes the acceleration of electron transfer. The 1T-2H MoS₂-S_v/CuS material exhibits an overpotential of 85 mV in the HER at a current density of 10 mA cm⁻², while it shows an overpotential of 100 mV in the OER at the same current density of 10 mA cm⁻², with a Tafel slope of 67 mV dec^-1. Additionally, 1T-2H MoS₂-S_v/CuS exhibits excellent stability in both HER and OER. The work provides a new strategy for constructing MoS₂-based composites exhibiting dual-functional, highly efficient HER and OER performance.