Effect of pH values on the structural, optical and electrical properties of SnO2 nanostructures

In the present work, we have synthesized the SnO2 nanostructures via precipitation method under optimal conditions at different pH values (3, 7 and 11) and studied the effect of different pH values on the structural, optical and electrical properties. The prepared samples are characterized by XRD, FESEM, TEM, PL, UV-vis, FTIR spectroscopy and EIS measurements. XRD analysis reveals the tetragonal crystal structure for the prepared SnO2 nanostructures. TEM images show that the morphology of SnO2 nanostructures changed from spherical to hexagonal as pH values increased from 3 to 11. The deconvoluted PL spectra show various defects present in the synthesized samples that act as luminescent centers. The absorption spectra revealed that the maximum optical band-gap is obtained for SnO2 nanostructures synthesized using acidic solutions. The FTIR spectrum verifies the presence of stretching vibration mode of O-Sn-O bond and, stretching and bending bonds of O-H bonds in the prepared samples. A detailed exploration on frequency and temperature dependent impedance properties of SnO2 nanostructures has been done with the change in pH values.