Shape and phase-controlled synthesis of specially designed 2D morphologies of l-cysteine surface capped covellite (CuS) and chalcocite (Cu2S) with excellent photocatalytic properties in the visible spectrum

Abstract

Two dimensional (2D) nanomaterials have interesting properties due to their lateral dimensions. Pure self-assembled l-cysteine stabilized covellite nanoplates (CuS@L-Cys NPs) and l-cysteine stabilized chalcocite nano leaves (Cu2S@L-Cys NLs) were synthesized by using a template free, the facile hydrothermal route with the best control of size, phase purity structure, morphology, and electrochemical properties. Novel CuS@L-Cys NPs and Cu2S@L-Cys NLs snowflakes dendrites were synthesized by varying synthetic parameters such as solvent, temperature (100–180 °C), reaction time (8–24 h), pH of reaction medium (7–14), the concentration of base (0.1–2.4 mL NH3) and concentration of thiourea (1–4 mmol). By changing these factors, different morphologies such as irregular, regular, trigonal, hexagonal leaf and snowflakes dendrites like shapes were observed. CuS@L-Cys NPs and Cu2S@L-Cys NLs were fabricated by using water and ethylenediamine (EDA) as solvent respectively. CuS@L-Cys NPs and Cu2S@L-Cys NLs were investigated for potential photocatalytic applications in methyl orange (MO) degradation under visible light with a detailed mechanism. The noteworthy, unique bandgap of 2 eV and the special morphology of CuS@L-Cys NPs increases the active sites for adsorption of dye, which causes extraordinary degradation activity. Furthermore, the l-cysteine (L-Cys) protective layer could efficiently alleviate the photocorrosion of CuS and Cu2S, giving rise to excellent stability.