Sunlight assisted photodegradation by tin oxide quantum dots

• SnO2 QDs of size 2.5 nm were synthesized by a surfactant free chemical route at a temperature of 70 °C.
• SnO2 QDs are of rutile structure with a large number of oxygen vacancies as evidenced by Raman and PL spectra.
• Sunlight assisted photodegradation by SnO2 QDs with vanillin shows an efficiency of 87%.
• Photodegradation efficiency and PL of SnO2 QDs decrease with increase in annealing temperature.

Rutile phase of SnO2 quantum dots of average size of 2.5 nm were synthesized at a growth temperature of 70 °C and characterized with XRD, TEM, FTIR and Raman analysis. The effective strain within the lattice of SnO2 quantum dots was calculated by Williamson–Hall method. The broad peaks in XRD as well as Raman spectra and the presence of Raman bands at 569 and 432 cm−1 are due to lower crystallinity of nanoparticles. The optical band gap of SnO2 quantum dots was increased to 3.75 eV attributed to the quantum size effect. SnO2 quantum dots were annealed in air atmosphere and the crystallite size of the particles increased with annealing temperature. Sunlight assisted photodegration property of SnO2 quantum dots was investigated with vanillin as a model system and it shows the photodegradation efficiency of 87%. The photoluminescence and photodegradation efficiency of nanocrystallite SnO2 decreases with increase of crystallite size contributed to the reduction in population of defects and surface area.