Co-electrodeposited Ag₂SnS₃/Mo thin films: optical and electrochemical study: DFT complement

This study concerns the synthesis of the Ag₂SnS₃ phase on a molybdenum (Mo) substrate, using the coelectrodeposition-sulfurization process by adjusting the [Ag⁺] at 0.01 M. XRD, Raman, UV–visible and electrochemical analyses have shown that Ag₂SnS₃/Mo films have been well elaborated with remarkable properties for practical applications. Optically, when [Ag⁺] was varied between 0.01 and 0.02 M, Ag₂SnS₃ films present a bandgap change in the range 1.20–1.36 eV, with an absorption coefficient of around 10^–4 cm⁻¹. Whereas the DFT → GGA calculation was implemented as a confirmatory theoretical study of the semiconductor and optical aspects of this Ag₂SnS₃ compound whilst comparing results with experiment. A further attractive property was demonstrated here by an electrochemical study of Ag₂SnS₃/Mo in Na₂SO₄ (1 M) under the (− 900, 100) mV/SCE potential window. More specifically, cyclic-voltammetry analysis has highlighted its pseudo-capacitor character with a developed specific capacitance of 800 F g⁻¹, while galvanostatic charge–discharge shows a drop of around 35% when the current is reduced from 0.5 to 3 mA.