Synthesis of nanostructured In2O3 ceramics via a green and chemical method for the mineralization of crystal violet dye: A comparative study

Abstract

Herein, the photocatalytic capabilities of indium oxide nanoparticles obtained by Aerva javanica extract synthesis and surfactant-mediated co-precipitation synthesis were studied using crystal violet (CV) as a model dye. Indium oxide nanoparticles synthesized via green (In2O3-G) and chemical route (In2O3-C) were characterized through different spectroscopic, structural, electrical and morphological analyses. The plant extract’s metabolites (flavonoids) effectively reduce the indium metal and induce oxygen vacancies, which develop sub-energy levels below the conduction band and hence increase the current conductivity and reduce the optical band of the photocatalyst. The above-mentioned structural modifications improve the In2O3-G photocatalyst's light-harvesting capacity and charge transport characteristics. Optical and current–voltage measurements show that the In2O3-G photocatalyst has more outstanding electrical conductivity (σ = 1.76 × 10-3 Sm−1) and bandgap (Eg = 2.93 eV) more compatible with the visible light than its counterpart (In2O3-C). Due to their amine, carboxyl, and hydroxyl functionalities, the plant extract's metabolites controlled and facilitated the synthesis of In2O3-G in the nanosized range. The integration of some crucial features such as higher surface area, faster charger transport properties, and a visible light-compatible band gap enable our In2O3-G photocatalyst to mineralize 93.75% CV dye in just 80 min with 0.027 min−1 rate-constant. This research demonstrates that a green approach to producing ceramic photocatalysts is preferable to chemical methods, which are more costly and create additional environmental issues.