Reinforced photocatalytic reduction of SnO2 nanoparticle by La incorporation for efficient photodegradation under visible light irradiation

Abstract

In this era of technology, evolving and understanding the physicochemical properties of a novel photocatalytic material to degrade organic species in polluted water is most needed all over the globe due to environmental production. This study reports the influence of lanthanum (La) in physicochemical properties of tin (II) dioxide (SnO2) nanoparticles and its application towards methylene blue (MB) degradation under sunlight. The SnO2, 2 mol% La incorporated SnO2 and 4 mol% La incorporated SnO2 (4 mol% La) nanoparticles were synthesized by simple co-precipitation method and characterized. X-ray diffraction patterns indicate higher angle shifts and peak broadening with respect to increase in La concentration. High-resolution transmission electron microscopic images (HR-TEM) reveal that SnO2 particle size decreases with respect to increase in La concentration. Morphological analysis shows that addition of La changes SnO2 morphology from agglomeration to segregated porous nature. Energy dispersive spectrum confirms the presence of parent and dopant elements in La incorporated SnO2 nanoparticles. UV–Visible spectrum indicates the increase in the band gap of La incorporated SnO2 due to the quantum size effect. The surface disorder, reduction in particle size and phonon confinement are identified from the Raman spectral analysis. Moreover, electrochemical analysis demonstrates the possible electrochemical activity of the materials as well as confirms that La provides higher charge transfer kinetics and stability to SnO2 nanoparticle. In addition, the calculated CBM potential confirms that La increases the redox potential of SnO2 nanoparticle, which is an ample condition to reduce O2 as ·O2−. The fast MB degradation kinetics achieved by 4 mol% La-SnO2 nanoparticle, which degrades 99% of MB within 60 min under sunlight irradiation and exhibits more than 90% photodegradation efficiency up to ten recycle. A through study of possible photocatalytic mechanism for the photocatalytic degradation is discussed.