Improved photocatalytic performance of nanostructured SnO2 via addition of alkaline earth metals (Ba2+, Ca2+ and Mg2+) under visible light irradiation

Pure and alkaline earth metal (Ba 2+ , Ca 2+ and Mg 2+ )-doped tin oxide nanoparticles were synthesized by simple co-precipitation, and their structural, optical, functional, morphological and compositional properties were analyzed in detail using powder X-ray diffraction, UV–visible spectroscopy, photoluminescence spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy and energy-dispersive analysis of X-ray (EDAX). XRD revealed the formation of rutile tetragonal structure, and the crystallite size has decreased from 28 to 24 nm by the addition of alkaline metal dopants. FTIR spectra confirmed the presence of fundamental vibration modes of SnO 2 . The optical band gap energy was decreased to 3.05, 3.19 and 2.98 eV by introducing Ba 2+ , Ca 2+ and Mg 2+ ions, respectively. Photoluminescence spectra showed defect-related emission peaks, and their intensities were found to increase in doped SnO 2 samples. EDAX spectra confirmed the presence of Sn, O, Ba, Ca and Mg elements. The photocatalytic activity of pure and alkaline metal-doped SnO 2 catalyst has been investigated under visible light irradiation by using methylene blue dye. The results showed that the Mg-doped SnO 2 catalyst has a higher photodegradation efficiency (~ 95.7%) compared with other investigated samples.