Impact of pH variation and radical scavenger on photocatalytic dye degradation of Rhodamine B dye using LaAlO3/ZnO nanocomposites synthesize by sol gel method

Abstract

A series of LAZO(LaAlO₃/ZnO) nanocomposites with varying ZnO contents (1:1,1:3,1:5, and 1:7) have been effectively prepared using the Pechini sol-gel method. Structural analyses have been conducted using XRD and Rietveld refinement. The irregular shapes with porous morphology of nanocomposites captured by the FESEM and HRTEM studies and the presence of Zn, La, Al, and O elements have been confirmed by EDX spectroscopy. DRS technique corroborated bandgap values that lie in the range of 6.09–2.93 eV, while PL studies confirm a suppressed charge carrier recombination with increased concentrations of ZnO in the nanocomposite. The negative surface potential has been assessed by the Zeta analyzer, which indicates its suitability for the degradation of cationic dyes such as Rhodamine-B (RhB). The photocatalytic activity of LAZO nanocomposites in degrading RhB dye is significantly higher than that of pure ZnO and LAO under UV irradiation. Among the samples, LAZO (1:5) has the highest efficiency (∼97 %) in degrading RhB dye within 100 min. The effect of pH on the reaction medium and the role of reactive oxygen species were also examined. In the neutral medium, almost complete degradation of dye is achieved in 100 min. Radical trap experiments reveal that holes are the main oxidative species part in the degradation of RhB dye. The adsorption kinetic are best described by Pseudo second order kinetic model. Type I heterojunction charge transfer mechanism well explains the degradation pathway of RhB dye. The development of nanocomposite photocatalysts that facilitate efficient charge transfer mechanisms is a promising strategy for improving photocatalytic activity and removing organic contaminants from water sources.