Shatendra Sharma*, Monika Vats, Jyotsna Sharma, Arvind Chhabra, R. K. Rakesh Kumar and Cheng-Hsin Chuang Pages 1 - 8 ( 8 )
Background: Tin oxide nano-particles also show good photo-catalytic efficiency because of its wide band gap and high recombination rates of photo-generated electron-hole pairs. Being non-toxic and chemically stable, the tin oxide nano-particles are used as dynamic photo-catalyst for the degradation. Tin oxide nano-crystals suitable for charge storage devices are synthesized using co-precipitation technique.
Objectives: Synthesis of Tin oxide nano-crystals by using co-precipitation method for photo-catalytic activity under sunlight that can be used for photo-degradation. The method of synthesis and characterization are discussed.
Materials and Methods: The nano-crystals are prepared by co-precipitation method using stannic chloride and sodium carbonate. sodium carbonate is added under constant stirring drop by drop for 90 minutes. The solution is settled for 4 hours. The precipitates are first washed using de-ionized water and then with ethyl alcohol. The dried powder of nanocrystals is then calcinated at 500oC for one hour in a muffle furnace. The structural, morphological, optical and electrical characterization of these synthesized crystals is done using (XRD), (FESEM), (TEM), (UV-Visible), (FT-Raman), Zeta potential and dielectric constant measurements.
Results and Discussion: The sizes of synthesized nano-crystals vary from 25 nm to 100 nm and are found to be optically transparent. The dielectric constant of nano-crystals is measured in the frequency range of 100Hz-1MHz and it can be seen that it declines from ~2000 at frequency 100Hz to ~30 at 1MHz.However, this decline in dielectric constant with frequency can be explained well on the basis of strong space charge polarization and rotational direction polarization processes in nanostructures. In the high frequency regions, these processes cannot follow the electrical field frequency variations that results in the rapid decrease of dielectric constant. Photo-catalytic activity: The photo-catalytic activity of the particles under sun light is also investigated which shows that the crystals show degradation of the methylene blue dye under sunlight irradiation.
Theoretical investigations with DFT: The band gap of the particles is also calculated from the UV-VIS spectra which is found to be ~3.6 eV and this experimentally observed value of band gap matches with that calculated theoretically from Density Functional Theory (DFT) using Local Density Approximation (LDA).
Conclusion: The method of synthesis reported in the present paper is scalable and can be used for commercial synthesis of SnO2 nano-crystals for electrodes and energy storage devices.
Tin oxide, co-precipitation, nanocrystals, characterization, photo-degradation, photocatalytic activity, DFT calculations, Dielectric constant
USIC and School of Engineering, Jawaharlal Nehru University, New Delhi-110067, Amity School of Applied Sciences, Amity University Haryana,Gurugram-122413, Amity School of Applied Sciences, Amity University Haryana,Gurugram-122413, Stem Cell Institute, Amity University Haryana,Gurugram-122413, Institute of Medical Science and Technology, National Sun Yat-sen University, Institute of Medical Science and Technology, National Sun Yat-sen University