Phase controllable synthesis of CuS nanoparticles by chemical co-precipitation method: Effect of copper precursors on the properties of CuS

The studies focusing on the synthesis of CuS nanoparticles (NPs) by Chemical Co-Precipitation method (CCP) along with detailed growth mechanism are limited. In addition, the synthesis of CuS NPs in water solvent is highly encouraged as water is served as the best eco-friendly solvent. In the present report, taking the advantage of Cu+1 oxidation in the aqueous medium, CuS NPs were synthesized using CuCl and thiourea (Tu) via CCP in presence of naturally abundant water solvent under open atmosphere. In addition, the effect of different copper precursors (such as CuCl, CuCl2, and CuSO4 in combination with thiourea) and the mole ratio of Cu/S on the properties of CuS NPs were also investigated. XRD analysis showed the single-phase CuS for the combination of CuCl + Tu at Cu/S = 1:2 and CuCl2 (or CuSO4) + Tu at Cu/S = 1:1. For other growth conditions, copper-rich composition with mixed phases was observed. XPS analysis showed both +1 and + 2 oxidation states for copper in CuS NPs synthesized from CuCl and Tu at Cu/S = 1:2. The CuS NPs showed broad absorptions in the UV-Vis and NIR regions due to excitonic absorption and localized surface plasmon resonance (LSPR). The optical band gap energy of CuS NPs was varied in the range of 2.05-2.34 eV, depending on the type of copper precursor and Cu/S mole ratio used. The synthesized CuS NPs have potential applications in the visible solar light-driven dye degradation.