Comparative Study of the Structure, Composition, and Electrocatalytic Performance of Hydrogen Evolution in MoSx~2+δ/Mo and MoSx~3+δ Films Obtained by Pulsed Laser Deposition

Abstract

Systematic and in-depth studies of the structure, composition, and efficiency of hydrogen evolution reactions (HERs) in MoSx films, obtained by means of on- and off-axis pulsed laser deposition (PLD) from a MoS2 target, have been performed. The use of on-axis PLD (a standard configuration of PLD) in a buffer of Ar gas, with an optimal pressure, has allowed for the formation of porous hybrid films that consist of Mo particles which support a thin MoSx~2+δ (δ of ~0.7) film. The HER performance of MoSx~2+δ/Mo films increases with increased loading and reaches the highest value at a loading of ~240 μg/cm2. For off-axis PLD, the substrate was located along the axis of expansion of the laser plume and the film was formed via the deposition of the atomic component of the plume, which was scattered in Ar molecules. This made it possible to obtain homogeneous MoSx~3+δ (δ~0.8–1.1) films. The HER performances of these films reached saturation at a loading value of ~163 μg/cm2. The MoSx~3+δ films possessed higher catalytic activities in terms of the turnover frequency of their HERs. However, to achieve the current density of 10 mA/cm2, the lowest over voltages were −162 mV and −150 mV for the films obtained by off- and on-axis PLD, respectively. Measurements of electrochemical characteristics indicated that the differences in the achievable HER performances of these films could be caused by their unique morphological properties.

Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature

“…This circumstance may explain the formation of a rather dense structure in the deposited MoS x coatings. If the ion bombardment of MoS x coatings (which are formed through the deposition of Mo and S atoms) is absent or ineffective, there is a tendency toward a porous column structure with a cauliflower morphology [37]. Figure 2 shows the results of the XRD studies of MoS x coatings.…”

On the Dynamics of Transient Plasmas Generated by Nanosecond Laser Ablation of Several Metals

“…With such complex distributions seen for all investigated plasmas with multiple maxima and possible NP-induced structures, the control of plasma energy during the deposition becomes essential. Several routes for controlling the plasma kinetics are proposed in the literature including but not limited to fluence reduction [ 2 , 36 ], background gas addition [ 22 , 37 , 38 ], off-axis deposition [ 39 ], etc. The control from laser fluence can be challenging as changes in the transferred energy towards the target strongly affects the fundamental ablation mechanisms and often leads to the formation of clusters and droplets on the deposited film [ 40 , 41 ], which is undesirable.…”

Application of Pulsed Laser Deposition in the Preparation of a Promising MoSx/WSe2/C(В) Photocathode for Photo-Assisted Electrochemical Hydrogen Evolution

“…Experiential studies of amorphous molybdenum sulfide (a-MoS x ) catalytic film creation have shown that, during off-axis PLD, the buffer gas has the conditions necessary for the effective saturation of films with chalcogen atoms [28]. These conditions are a result of the difference between the S and Mo atomic masses.…”

“…The most common technique to obtain such films is a chemical synthesis or chemical deposition in the solutions of special precursors. The applicability of a laser-based technique to create amorphous a-MoS x films with good electrocatalytic properties has been described in the literature [28,[32][33][34][35]. Fominski et al demonstrate that the PLD technique is associated with the highest catalytic activity in MoS x~4 films because they contain Mo 3 S 12 /Mo 3 S13 clusters [35].…”