Sulphur precursor dependent crystallinity and optical properties of solution grown Cu₂FeSnS₄ particles

Herein, Cu₂FeSnS₄ (CFTS) particles are synthesized using solvothermal method and the effects of different sulphur precursors (thiourea/thioacetamide/sulphur powder/sodium sulphide) on crystallinity, morphology and elemental composition are investigated. The CFTS particles have noticeable variation in elemental composition, when different sulphur precursors are used in the synthesis. Further annealing in sulphur atmosphere the stoichiometric ratio of CFTS particles improves and the binary/impurity phases are reduced. Among the four different sulphur precursors, the thiourea results in the better crystallinity and larger size grains of CFTS particles. The use of different sulphur precursor also renders significant change in the morphology of CFTS particles. The optical band gap of CFTS particles is also varied from 1.48 eV to 1.81 eV due to significant difference in crystallinity, composition and morphology. A better photocatalytic performance is observed in the CFTS particles which are grown using thiourea and approximate 70% methylene blue dye is degraded in 60 min under white light excitation.