Pulsed Laser Deposition of Nanostructured MoS3/np-Mo//WO3−y Hybrid Catalyst for Enhanced (Photo) Electrochemical Hydrogen Evolution

Abstract

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 WO3−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 WO3−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//WO3−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 WO3−y films) with the same loading. Modeling by the kinetic Monte Carlo method indicated that the change in morphology of the deposited WO3−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.

Porous Tungsten Oxide: Recent Advances in Design, Synthesis, and Applications

“…The saturation efficiency of WO 3 is improved by using oxygen as a reactive background atmosphere. [55]…”

“…The use of dry air with pressures allowed the formation of porous WO 3 films as shown in Figure 6c. The saturation efficiency of WO 3 is improved by using oxygen as a reactive background atmosphere [55] …”

Performance and Mechanism of Photoelectrocatalytic Activity of MoSx/WO3 Heterostructures Obtained by Reactive Pulsed Laser Deposition for Water Splitting

“…After W and Mo targets and substrates were installed in the chamber to obtain films, the chamber was pumped out by a turbomolecular pump to a pressure of~10 −3 Pa. Then, dry air was let into the chamber to a predetermined pressure, and the target W was ablated. Based on the results of previous studies by Fominski et al [20], three dry air pressures of 20, 40, and 60 Pa were chosen to produce WO y films. The temperature of the substrate was 420 • C. The deposition time of tungsten oxide films was 20 min.…”

“…The use of this material to activate the hydrogen evolution reaction (HER) is constrained by the complexity of the formation of a specific structural and chemical state in WO 3 , which has high catalytic activity [18,19]. For this reason, various hybrid-and hetero-structures based on tungsten oxide are currently being developed [20][21][22][23][24][25]. In these structures, the (photo-) electrocatalytic activity of tungsten oxide is enhanced by the deposition of films (co-catalysts) that have a positive effect both on the efficiency of the electrocatalytic process of hydrogen evolution and on the processes of generation and transport of non-equilibrium carriers in a hybrid-or hetero-structure.…”

“…In these structures, the (photo-) electrocatalytic activity of tungsten oxide is enhanced by the deposition of films (co-catalysts) that have a positive effect both on the efficiency of the electrocatalytic process of hydrogen evolution and on the processes of generation and transport of non-equilibrium carriers in a hybrid-or hetero-structure. Previously, Fominski et al [20] showed that the efficiency of the photoelectrocatalytic HER process on WO 3−y porous films can be significantly increased by the deposition of a MoS x~3 /np-Mo nanofilm. MoS 3 /np-Mo films were produced by PLD from a MoS 2 target in a buffer gas.…”