Tb-doped SnO2 nanostructures for fluorescence sensing and dye degradation applications

Facile hydrothermal method has been successfully used to synthesize Tb-doped SnO2 (Tb:SnO2) samples. Several analytical techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, Brunauer Emmett Teller (BET) analysis, ultraviolet–visible spectroscopy and photoluminescence spectroscopy have been used for the characterization of as-synthesized samples. It has been observed that doping concentration play a significant role in regulating morphology of as-synthesized SnO2 nanostructures. XRD patterns show tetragonal rutile structure of all the samples alongwith shrinkage of lattice with the increase in doping concentration. FESEM images indicate the formation of structures with different morphologies by varying doping concentration. The band gap energy of doped samples was found to increase with the increase in doping concentration. For the application prospective, sensing and photocatalytic behaviour of undoped and Tb:SnO2 samples has been examined. About 90% degradation of Rhodamine-B (RhB) dye was observed within 70 min by 10 mol% Tb-doped SnO2 nanostructures. Further, 10 mol% Tb-doped SnO2 nanostructures exhibits high-sensitivity towards Cd2+ with very low detection limit of 0.007 µg/ml compared to other doped SnO2 nanostructures. The improved photocatalytic and sensing behaviour of 10 mol% Tb-doped SnO2 nanostructures towards photodegradation of RhB and sensing of Cd2+ions was attributed to the enhanced surface area as seen from BET measurements and specific morphology alongwith efficient separation of charge carriers.