Nano-sized SnO₂ by a facile nanosecond laser irradiation in aqueous solution

A green and facile route was devised for the synthesis of SnO₂ nanoparticles (NPs) using pulse laser irradiation of an aqueous solution of stannous chloride dihydrate and sodium hydroxide. The process employed ascorbic acid as a passivating agent, and SnO₂ was obtained without any hazardous chemical reducing agent or high temperature calcination process. A nanosecond laser generating pulses with a peak wavelength of 355 nm and pulse repetition rate of 10 Hz was employed. Structural characterisations of the as-synthesized nanoparticles were carried out. The morphology of the SnO₂ NPs were mostly spherical and their average crystalline sizes in the range 48.0–62.5 nm as obtained from the TEM images. The particles size showed a direct relationship with the irradiation time, and a decrease in the monodispersity was observed with increase in the time of exposure to the laser beam. The photocatalytic activity of the NPs, obtained with the least time of exposure to the laser beam, was evaluated for the photodegradation of methylene blue under visible light. The nanoparticles achieved about 84% efficiency towards the degradation of the dye within 180 min. (paper)