Synergistic effects of noble metal doping and nanoengineering on boosting the azo dye mineralization activity of nickel oxide

Abstract

The present investigation involves the synthesis of a nanostructured ceramic material, namely silver-doped nickel oxide (Ni1−x(Ag)xO), by a wet-chemical method supported by a surfactant. The physicochemical, electrical, textural, compositional, and optical characteristics of nickel oxide and its Ag-doped variant were assessed using several analytical procedures, comprising X-ray diffraction, FTIR, current-voltage testing, scanning electron microscopy (SEM), elemental (EDX), and photoluminescence analysis. These materials were then used as a photocatalyst under W-light exposure to examine the annihilation of a hazardous azo dye (crystal violet). Under optimal circumstances (pH = 9, photocatalyst dosage = 0.01 g/80 mL, dye concentration = 15 ppm, reaction time = 80 min), Ag-doped nickel oxide nanocatalyst displayed more potent dye annihilation activity than pure nanocatalyst. The Ag-doped nickel oxide nanocatalyst exhibits a significant degradation efficiency of 94.44% towards Crystal violet (CV) dye, and it lost just 7.5% efficacy after four consecutive reusability tests. The degradation process used hydroxyl radicals as principal active species and followed a pseudo-1st order kinetic model with a rate constant (k) value of 0.024 min−1. Incorporating silver in the crystal structure of nickel oxide as a dopant effectively reduces the band gap energy, therefore facilitating the absorption of a broader range of light wavelengths. Additionally, the presence of silver helps to mitigate electron-hole recombination, a process that may hinder the efficiency of photocatalysis. Using nanotechnology in combination with silver doping improves the surface properties of the photocatalyst. These approaches work together to boost the photocatalytic activity of nickel oxide. This study proposes a novel methodology to enhance the photocatalytic capabilities of a basic ceramic material, making it a promising candidate for environmental remediation.