Pulsed Laser Deposition of Nanostructured MoS₃/np-Mo//WO_{3- y} Hybrid Catalyst for Enhanced (Photo) Electrochemical Hydrogen Evolution

Pulsed laser ablation of MoS₂ and WO₃ targets at appropriate pressures of background gas (Ar, air) were used for the preparation of new hybrid nanostructured catalytic films for hydrogen production in an acid solution. The films consisted of a nanostructured WO_3-y underlayer that was covered with composite MoS₃/np-Mo nanocatalyst. The use of dry air with pressures of 40 and 80 Pa allowed the formation of porous WO_3-y films with cauliflower- and web-like morphology, respectively. The ablation of the MoS₂ target in Ar gas at a pressure of 16 Pa resulted in the formation of amorphous MoS₃ films and spherical Mo nanoparticles. The hybrid MoS₃/np-Mo//WO_3-y films deposited on transparent conducting substrates possessed the enhanced (photo)electrocatalytic performance in comparison with that of any pristine one (MoS₃/np-Mo or WO_3-y films) with the same loading. Modeling by the kinetic Monte Carlo method indicated that the change in morphology of the deposited WO_3-y films could be caused by the transition of ballistic deposition to diffusion limited aggregation of structural units (atoms/clusters) under background gas pressure growth. The factors and mechanisms contributing to the enhancement of the electrocatalytic activity of hybrid nanostructured films and facilitating the effective photo-activation of hydrogen evolution in these films are considered.