Pulsed laser deposition and characterization of nanostructured thin films based on Mo(Ni)Sex and amorphous carbon phase as electrocatalysts for hydrogen evolution reaction

Abstract

Thin films of Mo(Ni)Se_x are synthesized using pulsed laser deposition (PLD) in a special mode of operation in which the laser ablation of a Mo(Ni)Se₂ target releases a mixed deposition flux consisting of atomic Mo, Ni, and Se and Mo droplets. The size of deposited Mo particles is in the range of 20–100 nm. Incorporation of amorphous carbon phase (a-C) in some Mo(Ni)Se_x films is achieved by using a graphite target along with a Mo(Ni)Se₂ one and depositing the ablation plume of the former. The films are deposited on graphite and glassy carbon substrates and some are subjected to thermal treatment at 550°C. Electrochemical testing for catalytic activity toward hydrogen evolution reaction (HER) and characterization of the structures are performed for both thermally processed and unprocessed samples. Annealing is shown to cause the formation of structures with the inclusion of ultrafine sheetlike MoSe₂ crystals. Incorporation of carbon in the films suppresses the growth of the nanosheets during annealing. However, enhancement of HER in an acidic solution is also observed for samples with quite minor amounts of the nanosheets, which can be attributed to peculiarities of structurization of Mo(Ni)Se_x and Mo(Ni)Se_x/a-C layers obtained by PLD.