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

Abstract

We studied the possibility of using pulsed laser deposition (PLD) for the formation of a MoSx/WSe2 heterostructure on a dielectric substrate. The heterostructure can be employed for effective solar water splitting to produce hydrogen. The sapphire substrate with the conducting C(B) film (rear contact) helped increase the formation temperature of the WSe2 film to obtain the film consisting of 2H-WSe2 near-perfect nanocrystals. The WSe2 film was obtained by off-axis PLD in Ar gas. The laser plume from a WSe2 target was directed along the substrate surface. The preferential scattering of selenium on Ar molecules contributed to the effective saturation of the WSe2 film with chalcogen. Nano-structural WSe2 film were coated by reactive PLD with a nanofilm of catalytically active amorphous MoSx~4. It was established that the mutual arrangement of energy bands in the WSe2 and MoSx~4 films facilitated the separation of electrons and holes at the interface and electrons moved to the catalytically active MoSx~4. The current density during light-assisted hydrogen evolution was above ~3 mA/cm2 (at zero potential), whilst the onset potential reached 400 mV under irradiation with an intensity of 100 mW/cm2 in an acidic solution. Factors that may affect the HER performance of MoSx~4/WSe2/C(В) structure are discussed.

Enhanced Tribological Performance of Low-Friction Nanocomposite WSexSy/NP-W Coatings Prepared by Reactive PLD

“…Figure 5 a–c shows XPS spectra measured for as-deposited WSe x /NP-W and WSe x S y /NP-W coatings. The analysis of the W4f spectra reveals the presence of W 0 , W 4+ , and W 6+ species [ 52 , 53 , 54 ]. The dominance of W 4+ and W 6+ states is due to tungsten’s chemical bonds with chalcogen atoms (WSe 2 /WS 2 ) and oxygen (WO 3 ), respectively.…”

Pulsed Laser Phosphorus Doping and Nanocomposite Catalysts Deposition in Forming a-MoSx/NP-Mo//n+p-Si Photocathodes for Efficient Solar Hydrogen Production

“…The band gap width of the silicon was set at 1.1 eV. For the energy band width of the a-MoS x /NP-Mo film, a value was chosen that is typical for amorphous a-MoS x , ~1.5 eV [5]. When illuminating the photocathode with a ~4 nm thick catalyst film, tunneling of electrons, which accumulate in n + -Si layer, is possible to the catalytically active surface of a-MoS x /NP-Mo.…”

“…Because of their promising potential in hydrogen production technology by electrochemical (EC) and photoelectrochemical (PEC) water splitting, amorphous molybdenum sulfides (a-MoS x ), such as nanoclustered Mo 3 S 4 /Mo 3 S 12 /Mo 3 S 13 , have been widely developed and investigated since 2011 [1][2][3][4][5]. These nanomaterials have high concentrations of catalytically active sites, whose nature is still the subject of debate [6][7][8].…”

Controlled Deposition of Nanostructured Hierarchical TiO2 Thin Films by Low Pressure Supersonic Plasma Jets

“…The template-free fabrication of ordered TiO 2 nanostructured materials is also being actively investigated in an effort to devise a method that would enable a greater level of tunability of all material characteristics in a controlled and predictable manner. Indeed, techniques aimed at the production of thin films, such as physical vapor deposition (PVD) [ 22 ], plasma-enhanced chemical vapor deposition (PECVD) [ 23 , 24 ], and reactive pulsed laser deposition (PLD) [ 25 , 26 ] have had much success in realizing this objective. Another relevant technique is atomic layer deposition (ALD), which is nowadays one of the most versatile and controllable techniques for thin film deposition [ 27 , 28 ].…”