Influence of gadolinium substitution on the crystal structure of NiO and its maximized photocatalytic degradation activity on tetracycline and direct yellow pollutants

Abstract

Gadolinium-substituted NiO crystal structures with excellent stability were utilized for the first time to degrade antibiotic and organic dye pollutants. The present study investigated the effect of Gd³⁺ substitution on the NiO crystal structure and its increased photocatalytic degradation activities. A simple one-step hydrothermal technique procedure was used to synthesize different concentrations of Gd³⁺ substituted NiO, and the catalysts were thoroughly characterized using sophisticated techniques to explore the influence of Gd³⁺ on the crystal structure and optical characteristics of NiO. p-XRD, UV–Vis DRS, PL, HR-TEM, and HR-XPS techniques. The 1.5 % Gd³⁺ substituted NiO showed outstanding photocatalytic activity on against tetracycline and direct yellow degradation, with percentages of 90.72 and 95.5 %, respectively. The improvement of photocatalytic degradation efficiency is primarily due to the suppression of photoinduced electron and hole recombination via the creation of Gd³⁺ as the inner energy band state below the conduction band. The recycling experiments revealed that the catalyst is more stable, with no indication of loss after ten cycles. Scavenging investigations also demonstrated that superoxide and holes were responsible for the efficient degradation of pollutants.