Photocatalytic and fluorescent chemical sensing applications of La-doped ZnO nanoparticles

Abstract

Herein, we report the facile solution phase precipitation synthesis of ZnO nanoparticles doped with various concentrations, i.e. 1, 5 and 10 mol% of lanthanum (La). The synthesized nanoparticles were characterized in detail by several techniques which confirmed the high-density growth and well-crystalline nature of La-doped ZnO nanoparticles. The XRD results revealed the successful incorporation of 1 mol% La ions in the hexagonal wurtzite structure of ZnO; however, small XRD peaks of La2O3 were detected in 5 and 10 mol% La-doped samples. All the La-doped nanoparticles were found to be UV responsive. For the application prospective, all the synthesized nanoparticles were used as photocatalyst for the photocatalytic degradation of three toxic dyes, i.e. methyl orange (MO), Rhodamine B (Rh B) dyes and picric acid (PA). By detailed photocatalytic investigations, interestingly, 1 mol% La-doped ZnO was found to be most efficient photocatalyst towards the degradation of all three organic dyes. Further, the synthesized nanoparticles were also used as fluorescent probe for the fluorescence sensing of picric acid (PA). Remarkably, the 1 mol% nanoparticles exhibited highest sensitivity, i.e. lowest limit of detection (LOD) value (1.05 µM L−1) towards PA compared to 5 and 10 mol% (1.38 µM L−1) La-doped ZnO nanoparticles.