Enhanced electrocatalytic activity of MoS_x on TCNQ-treated electrode for hydrogen evolution reaction

Molybdenum sulfide has recently attracted much attention because of its low cost and excellent catalytical effects in the application of hydrogen evolution reaction (HER). To improve the HER efficiency, many researchers have extensively explored various avenues such as material modification, forming hybrid structures or modifying geometric morphology. In this work, we reported a significant enhancement in the electrocatalytic activity of the MoS_x via growing on Tetracyanoquinodimethane (TCNQ) treated carbon cloth, where the MoS_x was synthesized by thermolysis from the ammonium tetrathiomolybdate ((NH₄)₂MoS₄) precursor at 170 °C. The pyridinic N- and graphitic N-like species on the surface of carbon cloth arising from the TCNQ treatment facilitate the formation of Mo⁵⁺ and S₂^2- species in the MoS_x, especially with S₂^2- serving as an active site for HER. In addition, the smaller particle size of the MoS_x grown on TCNQ-treated carbon cloth reveals a high ratio of edge sites relative to basal plane sites, indicating the richer effective reaction sites and superior electrocatalytic characteristics. Hence, we reported a high hydrogen evolution rate for MoS_x on TCNQ-treated carbon cloth of 6408 mL g^-1 cm^-2 h^-1 (286 mmol g^-1 cm^-2 h^-1) at an overpotential of V = 0.2 V. This study provides the fundamental concepts useful in the design and preparation of transition metal dichalcogenide catalysts, beneficial in the development in clean energy.