Neodymium doped Bismuth oxybromide anchored graphitic carbon nitride Z-Scheme heterojunction photocatalyst for photodegradation of Acid Red 27 and Orange G dyes and its mechanism insights

Abstract

For the first time, a neodymium (Nd)-doped Bismuth oxybromide anchored with graphitic carbon nitride nanocomposite (NCs) was synthesized, and its photocatalytic performance was evaluated for dye degradation to address environmental pollution issues. Nd was selected as a dopant owing to its unique 4f electronic configuration, which introduces defect levels within the band gap, enhances visible-light absorption, and promotes efficient charge separation, thereby significantly improving photocatalytic activity for dye degradation. The synthesized materials include BiOBr:Nd (BN), g-C₃N₄ (CN), and a series of nanocomposites: BiOBr:Nd-CN-1 (BNCN-1), BiOBr:Nd-CN-2 (BNCN-2), BiOBr:Nd-CN-3 (BNCN-3), and BiOBr:Nd-CN-4 (BNCN-4), prepared via the coprecipitation method. XRD analysis confirmed the tetragonal phase of BiOBr in BN, with no distinct Nd peaks, indicating successful doping, while the (100) and (002) planes verified the formation of graphitic CN. In BNCN-1 and BNCN-2, CN related peaks were absent due to its lower concentration, whereas BNCN-3 and BNCN-4 displayed weak (002) peaks, confirming successful nanocomposite formation. Morphological analysis revealed Bi-based clusters embedded over thin CN layers, and TEM images confirmed a strong BN–g-C₃N₄ interface. BET analysis showed that BNCN-3 had the most favorable porous structure, correlating with superior photocatalytic efficiency. The band gaps, determined using diffuse reflectance spectra and Kubelka–Munk analysis, were 2.63, 2.86, 2.75, 2.60, 2.55, and 2.78 eV for BN, CN, BNCN-1, BNCN-2, BNCN-3, and BNCN-4, respectively. Under visible-light irradiation for 90 min, BNCN-3, achieved degradation efficiencies of 92.10 % for Orange G and 95.64 % for Acid Red 27. Scavenger tests revealed the dominant reactive species involved in the process, and the nanocomposite exhibited good reusability, demonstrating its potential as an efficient and sustainable photocatalyst for wastewater treatment.