Effect of ascorbic acid on the properties of tin sulfide films for supercapacitor application

Abstract

A novel synthesis of tin sulfide film was used for the first time when the film was prepared directly from abundant and biodegradable precursors via a simple SILAR (successive ionic layer adsorption and reaction) method at 40 °C. The structural, optical and electrochemical properties of tin sulfides are explored by changing the number (20 or 30) of SILAR cycles and the quantity of L-ascorbic acid (0.6-1.3 g). X-ray diffraction data showed the multiphase composition consisting of SnS and Sn2S3 in obtained films on fluorine doped tin oxide coated glass slides and Raman spectroscopy confirmed this. The most intensive peaks are assigned to mineral herzenbergite. Scanning electron microscopy showed that the films consist of densely packed irregular clusters of nanoparticles. The crystallite size was in the range of 9 - 15 nm and was dependent on the number of SILAR deposition cycles. The average size of the thickness of films varied from 310 to 1050 nm. The bandgap values calculated using ultraviolet-visible light spectroscopy data are very close to the theoretical values of herzenbergite (0.9- 1.3 eV). Electrochemical measurements showed that among all the films tested in this study, a tin sulfide film prepared with the lowest quantity of ascorbic acid is able to generate the highest specific capacitance of 6.35 F⋅g−1 with the best specific energy value of 3.53 Wh⋅kg−1. These results confirmed that the samples are promising candidates to be used as supercapacitors.