研究目的
The objective of this work was to perform a rather in-depth study of the main characteristics of MoSx films prepared by on- and off-axis PLD, and to determine the highest performance of HER that can be achieved with MoSx films deposited on glassy carbon substrates by these methods.
研究成果
The use of two modes of PLD from a MoS2 target allowed us to obtain amorphous MoSx-based catalysts with different compositions and morphologies. The hybrid structure somewhat slowed down the electric current transport through the deposited layer; however, this provided a greater physical surface area, and consequently, a greater number of active sites for HER. The porosity/morphology of the hybrid catalyst facilitated the effective growth of the exposed surface area with the increase in the MoSx~2+δ/Mo catalyst loading. The mode of off-axis PLD differs from the mode of on-axis PLD in terms of a higher deposition rate for catalytic MoSx~3+δ films and a larger S concentration in the amorphous MoSx~3+δ (δ ~0.8–1.1) phase.
研究不足
The technical and application constraints of the experiments include the difficulty in achieving uniform distributions of the MoSx catalyst over the entire surface areas of the samples and the potential for oxidation of the films when exposed to air.
1：Experimental Methods for the on- and off-Axis PLD of MoSx Films:
The substrates were located at a normal angle to the axis of laser plume expansion and were
2：5 cm from the target for on-axis PLD. Off-axis PLD was performed at an Ar pressure of 8 Pa, and the substrates were located 2 cm from the target. The MoS2 target was ablated by pulses from a Solar LQ529 laser. Structural and Electrochemical Characterization of the Prepared MoSx Films:
The MoSx films with different thicknesses were deposited at room temperature on substrates made of polished glassy carbon (GC), polished silicon plates, and NaCl crystals. The structures, compositions and surface morphologies of the MoSx films were studied using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM and EDS, Tescan LYRA 3), as well as micro-Raman spectroscopy (MRS), using a
3：8-nm (He-Ne) laser. The chemical states of the MoSx films were studied using X-ray photoelectron spectroscopy (XPS, K-Alpha apparatus, Thermo Scientific, Madison, WI53711, USA) with Al Kα radiation (6 eV). Electrocatalytic Performances of the MoSx~2+δ/Mo and MoSx~3+δ Films Prepared by on-Axis and off-Axis PLD:
6 The electrochemical studies of the MoSx films deposited on the GC substrates were performed in an H2-sparged 0.5 M H2SO4 aqueous solution using an Elins Instruments electrochemical analyzer (Model P-5X, Chernogolovka, Russia).
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