Fig. 3
a Chronopotentiometry during the deposition of molybdenum sulfide films, the samples named as S-0.2, S-0.4 and S-0.5 corresponding to the ammonium chloride concentration with 0.2 M, 0.4 M and 0.5 M, respectively. Inset: digital photo of an amorphous molybdenum sulfide film on Ti ingot. b Polarization curves for HER on bare Ti ingot and deposition on the Ti ingot of MoSx films of S-0.2, S-0.4 and S-0.5 and a high-pure Pt wire, scan rate = 5 mV s−1. c Tafel plot for the various catalysts derived from b. d Current densities curves at the overpotential of 150 mV, 200 mV and 250 mV, respectively