Carbonitride MXene Ti₃CN(OH)_x@MoS₂ hybrids as efficient electrocatalyst for enhanced hydrogen evolution

Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation, and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction (HER) are highly desirable. Herein, MoS₂ nanoflowers decorated two-dimensional carbonitride-based MXene Ti₃CN(OH)_x hybrids have been constructed by etching and post-hydrothermal methods. The electrochemical performance of the as-obtained Ti₃CN(OH)_x@MoS₂ hybrids having a quasi core–shell structure is fascinating: An overpotential of 120 mV and a Tafel slope of 64 mV∙dec⁻¹ can be delivered at a current density of 10 mA∙cm⁻². And after 3,000 cyclic voltammetry cycles, it can be seen that there is no apparent attenuation. Both the experimental results and density functional theory (DFT) calculations indicate that the synergetic effects between Ti₃CN(OH)_x and MoS₂ are responsible for the robust electrochemical HER performance. The electrons of –OH group in Ti₃CN(OH)_x are transferred to MoS₂, making the adsorption energy of the composite for H almost vanish. The metallic Ti₃CN(OH)_x is also beneficial to the fast charge transfer kinetics. The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices.