CdS nanocapsules and nanospheres as efficient solar light-driven photocatalysts for degradation of Congo red dye

Abstract

CdS-1 (nanosphers) and CdS-2 (nanocapsule), were synthesized via green synthetic route without using any toxic surfactants by thermolysis of bis(4-benzhydrylpiperazine-1-carbodithioate-κ2 S, Sʹ)cadmium(II) (1) and bis (4-benzylpipera-zine-1-carbodithioate-κ2 S, Sʹ)cadmium(II) (2), respectively in the presence of ethylenediamine as a solvent. The nanoparticles were characterized by TEM, XRD, SEM, FT-IR UV–Visible and Fluorescence spectroscopy. The TEM results showed the formation of nanospheres (CdS-1) and nanocapsules (CdS-2) from complexes 1 and 2, respectively. Both CdS nanoparticles (NPs) have hexagonal crystal phase and a band gap value in the visible region as confirmed by the XRD and UV–Visible spectra, respectively. The photoluminescence (PL) data revealed that CdS-2 has longer recombination time of photo-injected electron hole pairs than CdS-1. The similar FT-IR spectra for both CdS NPs, and different HOMO-LUMO gap values for complexes {4.8187 eV (1) and CdS-2 4.7504 eV (2)} as predicted by DFT calculations suggest that stability of complexes play a key role in controlling morphology. Furthermore, the visible light driven photocatalytic degradation of Congo red dye was observed higher for nanocapsules than nanospheres due to a longer recombination time of photo-injected electron hole pairs.