Solvothermally synthesized oxygen-deficient SnO2 for the degradation of methyl orange dye under sunlight and LED light irradiation
Rekha B. Rajput, Rohidas B. Kale
Abstract
A simple solvothermal method was used to efficiently synthesize rutile SnO2 nanoparticles with crystallite sizes ranging from 7 to 10 nm. The morphological observations revealed that the microparticles were formed by the aggregation of spherical nanoparticles, which were confirmed from SEM and TEM analysis. Also, the HRTEM analysis demonstrated that the nanoparticles observed by SEM and TEM are not single crystalline but rather composed of randomly oriented nanoparticles ranging in size from 3 to 5 nm. The EDS and XPS confirmed the presence of Sn and O; no other impurities were found. UV-vis study shows that the band gap value for SnO2 nanoparticles varies from 2.76 and 3.16 eV. The SnO2 nanoparticles are attributed to band edge emission, interstitial defect and homogeneous oxygen vacancies, as per the PL study measured at ambient temperature. The S1 sample was red-shifted compared to other samples, with a having surface area of about 45.2 m2/g, large pore size (5.82 nm) and large pore volume (0.081 cm3/g). That helps to achieve > 99 and 97% decomposition of MO within 6 and 25 min under sunlight and 9 W LED light irradiation, respectively. The scavenger test suggests that h+ radicals play a vital role in the photodegradation of MO dye.