CuS, In2S3 and CuInS2 nanoparticles by microwave-assisted solvothermal route and their electrochemical studies

Abstract The synthesis of CuS, In2S3 and CuInS2 nanoparticles by microwave irradiation of single source precursors is reported. Monodispersed nanoparticles with spherical morphology, whose average particle size were 2.3 nm (CuS) and 15.2 (In2S3) were obtained for the binary sulphides, while the ternary nanoparticles (CuInS2) displayed spindle shape morphology with some degree of agglomeration. The CuS, In2S3 and CuInS2 exhibited hexagonal, orthorhombic and wurtzite crystalline phases respectively. The electrochemical properties of the nanoparticles were studied using electronic impedance spectroscopy (EIS), cyclic and square wave voltammetry (CV and SWV). Results from the cyclic voltametric measurement showed that the modified electrodes exhibited a reversible redox reaction and typical faradic pseudo capacitance behaviour in 5 mM [Fe(CN)]4–/[Fe(CN)]3– aqueous electrolyte. The evaluated anodic current density of each electrode on a glassy carbon electrode (GCE) was found to follow the order: CuS (2.24 A/m2) > GCE (1.17 A/m2) > CuInS2 (0.699 A/m2) > In2S3 (0.632 A/m2), while the electroactive surface areas were 0.034, 0.0832 and 0.057 0 cm2 for GCECuS, GCEIn2S3 and GCECuInS2 respectively. The electron lifetimes of GCEbare, GCECuS, GCEIn2S3 and GCECuInS2 were also estimated, which gave 0.398, 0.275, 0.730 and 0.433 ms respectively. The lower charge transfer resistance and longer electron lifetime observed for the CuS nanoparticles compared to In2S3 and CuInS2 nanoparticles indicated a more efficient controlled surface for electrochemical process. Therefore, the nanoparticles could be employed as photoanodes in photovoltaic application to undergo oxidation on the electroactive species. EIS analysis of GCEIn2S3 and GCECuInS2 showed that the indium containing materials possess good electrocatalytic activity.