Visible-light-responsive Bi60In2O93 nanoparticles: synthesis and photocatalytic activity for energy and environmental applications

Abstract

Photocatalysis has emerged as an effective and sustainable approach for addressing environmental and energy challenges. In this study, Bi60In2O93 nanoparticles NPs were successfully synthesized via a hydrothermal method with varying Bi molar ratios. Structural and morphological characterizations were carried out using x-ray diffraction, Williamson–Hall (W–H) analysis, field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy. W–H analysis revealed a systematic increase in crystallite size from 30.5–72.0 nm with increasing bismuth content, accompanied by a rise in lattice microstrain from 1.87 × 10−4 to 14.1 × 10−4, indicating enhanced grain growth and structural evolution. FE-SEM analysis further confirmed this trend, showing an increase in average particle size from 61.2–77.7 nm at higher Bi:In ratios.Ultraviolet–Vis diffuse reflectance spectroscopy indicated band gap energies in the range of 2.67–3.15 eV, demonstrating improved visible-light absorption with increasing bismuth content. The photocatalytic performance was evaluated through the degradation of Rhodamine B under visible-light irradiation. Among the prepared samples, sample D exhibited the highest activity, achieving approximately 98% degradation within 45 min, with an apparent rate constant of 0.10082 min−1. The enhanced photocatalytic performance is attributed to the synergistic effects of band-gap narrowing, improved charge separation, and favorable nanostructure, which promote efficient generation of reactive oxygen species. These findings demonstrate that Bi60In2O93 nanoparticles are promising candidates for visible-light-driven photocatalytic applications.