Enhanced Photocatalytic Degradation of trypan Blue Dye by Copper Sulfide Nanoparticles Prepared from 4-Benzylpiperazinyldithiocarbamate Copper(II) Complex

The copper-(II) complex of 4-benzylpiperazinyldithiocarbamate was synthesized and characterized by spectroscopic techniques and single crystal X-ray crystallography. The single crystal X-ray structure of the compound revealed a centrosymmetric dimeric molecule with the copper-(II) ions situated in a distorted five-coordinate square pyramidal environment. The complex was used as a single source precursor for the preparation of copper sulfide nanoparticles capped with three capping agents, octadecylamine (ODA), dodecylamine (DDA), and hexadecylamine (HDA) and at three different temperatures, 120 °C, 160 °C and 220 °C. Powder X-ray diffraction patterns confirmed mainly chalcocite crystalline phases of copper sulfide with some minor peaks of roxbyite phase. The optical band gaps for the nanoparticles range from 4.07 to 4.16 eV, with a maximum absorption band edge of 283.7 nm. The morphological studies revealed different shapes ranging from spherical, hexagonal, and irregular shapes with average particle sizes ranging from 4.1 to 74.7 nm. The photocatalytic studies of the nanoparticles under visible light demonstrated an efficient photodegradation of trypan blue dye. Dodecylamine capped copper sulfide nanoparticles (CuS-DDA) and copper sulfide prepared at 120 °C (CuS-120) achieved 99.31% and 99.26% photocatalytic degradation efficiency with a rate constant of 0.03045 and 0.02749 min^-1, respectively. Scavenger studies revealed the role of reactive species in trypan blue degradation by copper sulfide nanoparticles. Recyclability experiments showed excellent stability and reusability of the nanoparticles, demonstrating their potential for sustained photocatalytic applications.