# “Sonochemically synthesized Ag(I) and Ni(II) schiff base complexes as efficient visible-light photocatalysts for dye degradation with DFT insights.”

## TL;DR

Scientists created new nanoscale complexes using silver and nickel that efficiently break down synthetic dyes in water under visible light, offering a reusable and eco-friendly solution for pollution.

## Contribution

The study introduces sonochemically synthesized Ag(I) and Ni(II) Schiff base complexes with high visible-light photocatalytic efficiency for dye degradation.

## Key findings

- Ag(I) and Ni(II) complexes achieved 95.3% and 91.7% Methylene Blue degradation under visible light.
- DFT calculations revealed reduced HOMO–LUMO gaps and enhanced thermodynamic stability in the complexes.
- The complexes showed excellent recyclability and pseudo-first-order kinetics in dye degradation.

## Abstract

Water pollution caused by synthetic dyes is a pressing environmental concern, necessitating the development of highly efficient and reusable photocatalysts. Herein, we report the sonochemical synthesis and comprehensive characterization of nanoscale Ag(I) and Ni(II) Schiff base complexes derived from an isatin–sulfathiazole ligand (H₂L). The complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility, FT-IR spectroscopy, ¹H NMR spectroscopy, UV–visible spectroscopy, XRD, TGA, and mass spectrometry. The obtained results confirmed their nanoscale dimensions, non-electrolytic behavior, and proposed tetrahedral geometries. TGA further assessed thermal stability and the presence of coordinated and lattice water molecules, with thermodynamic parameters calculated via the Coats–Redfern method. Complementary density functional theory (DFT) calculations provided detailed electronic and structural insights, supporting the proposed geometries and revealing reduced HOMO–LUMO energy gaps, distinct charge distribution patterns that highlight electron-rich and electron-deficient regions, and enhanced thermodynamic stability. Optical studies further confirmed the semiconducting nature of the synthesized compounds, consistent with their observed photocatalytic behavior. Both complexes exhibited remarkable photocatalytic performance under visible light, achieving Methylene Blue (MB) degradation efficiencies of 95.3% for the Ag(I) complex and 91.7% for the Ni(II) complex under optimized conditions (pH 11, 30 mg catalyst per 100 mL, and 10 ppm MB). Kinetic studies confirmed pseudo-first-order behavior, while recyclability tests demonstrated excellent stability and reusability over four consecutive cycles. These results highlight the potential of sonochemically synthesized Schiff base complexes as efficient, durable, and eco-friendly photocatalysts for wastewater treatment applications.

The online version contains supplementary material available at 10.1038/s41598-026-37498-8.