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.
Highlights
Transition metals chalcogenides have received considerable attention from scientists involved in the development of photoelectrochemical cells for producing hydrogen by solar water splitting [1,2,3]
Electrons will move into the MoSx layer from the WSe2 and participate in the hydrogen evolution reaction, whilst holes will move from MoSx into the WSe2 layer
A nanostructured WSe2 layer was grown on the C(B) contact layer
Summary
Transition metals chalcogenides have received considerable attention from scientists involved in the development of photoelectrochemical cells for producing hydrogen by solar water splitting [1,2,3] These semiconducting materials have physio-chemical properties that enable their usage as both photo-active materials and hydrogen evolution electrocatalysts [4,5,6]. The good catalytic properties of metal chalcogenides ( amorphous molybdenum sulfides MoSx ) allow the compounds to replace expensive platinum. They can ensure high efficiency of photo-assisted hydrogen evolution when using silicon-based heterostructures (n+p-Si) [7,8,9]. Efficient hydrogen evolution is usually achieved by using an expensive (Pt/Ru) cocatalyst [10,11]
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