Novel solution-processed amorphous WS2 thin films with efficient hydrogen evolution

Résumé fourni par la source

In this work, we report a novel fabrication of binder free 2D WS2 thin film from a single source precursor (WCl6) via spin coating followed by moderate temperature sulfurization. Electrochemical evaluation of such films showed efficient catalytic activity for hydrogen evolution reaction. The thickness of the obtained films was precisely controlled by varying the concentration of precursor solutions. Spectroscopic characteristics confirmed successful conversion of precursor materials into amorphous WS2 upon sulfurization. Raman and XPS results revealed the presence of minor WO3 in the fabricated WS2 films which make it more favorable for HER activity. Furthermore, XPS result also verified existence of sulfur vacancies in the WS2 films which serves as active site for HER. Electrochemical study revealed that thinner WS2 films exhibit superior performance, with 10 nm WS2 layer having an overpotential of 410 mV at 10 mA/cm2 and a Tafel slope of 71 mV/decade. Dual semicircles were observed in electrochemical impedance spectroscopy for thinner films, which corresponded to efficient charge transfer and lower resistance at the interfaces. Collectively, these findings (amorphous nature, WO3 doping and sulfur vacancies) contributed to an efficient HER catalytic performance. Hence, WS2 thin films obtained by simple spin coating is economical, scalable, simpler method for fabrication of WS2 film for sustainable hydrogen production.

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