Selective syntheses of kuramite (Cu2SnS3) and petrukite (Cu3SnS4) phases of copper tin sulphide, and their electrochemical and photocatalytic properties

Abstract

Semiconductor materials of the type Cu–Sn–S (CTS) have recently been the focus of intense research due to their unique optical and thermoelectric properties. Their properties are also tunable by varying reaction parameters such as precursor concentration, solvent chemistry and reaction temperature. In this study, two phases of CTS: Cu2SnS3 and Cu3SnS4, were synthesized by the co-thermolysis of two dithiocarbamate complexes through the tuning of reaction temperature and solvent type. Cu2SnS3 nanoparticles with average crystalline size of 13.1 nm and band gap energy of 1.16 eV were synthesized in oleylamine at 220 ̊C, while Cu3SnS4 nanoparticles with average size of 12.3 nm and band gap energy of 1.57 eV was obtained in a mixture of oleylamine and dodecanthiol at 180 ̊C. The electrochemical and photocatalytic properties of the two CTS phases were further studied, with the Cu2SnS3 phase showing better properties compared to the Cu3SnS4 phase. The ability to achieve phase selectivity in synthesizing CTS with different crystal structures and band gap energies in a facile solvothermal process could be valuable in developing semiconductor materials with unique properties.