Direct and in situ growth of 1T′ MoS2 and 1T MoSe2 on electrochemically synthesized MXene as an electrocatalyst for hydrogen generation

Crystal phase modulations in two-dimensional (2D) materials have garnered extensive interest because of their intriguing features and potential applications. Nonetheless, synthesizing some specific phases of metastable transition metal dichalcogenides (TMDs) remains a challenge due to the restricted selectivity under chemical and physical treatments, especially for direct growth of specific phase of TMDs on 2D substrates to form heterostructures. Taking the merits of MXene with tunable atomic vacancies and surface chemistry via surface functionalization, the phase of epitaxially grown TMDs on 2D MXene can be significantly affected. In this work, 1 T′-MoS2 and 1 T-MoSe2 were directly grown on electrochemically synthesized MXene under controlled oxidization conditions and selected MXene substrate. Owing to the synergistic effect of TMDs and MXene, the TMDs/MXene heterostructure catalysts exhibit good electrochemical activity under acidic conditions, with a low overpotential of 167 mV at a current density of 10 mA cm−2. Our work not only demonstrates the distinct chemical characteristic of various MXenes feasible for surface engineering which promotes the direct and in situ growth of phase controlled TMDs on MXene substrates but also displays the high electrochemical activity in TMDs/MXene heterostructure catalysts.