Effect of electrolytic media on the photophysical properties and photocatalytic activity of zinc oxide nanoparticles synthesized by simple electrochemical method.

Mesoporous ZnO nanoparticles (NPs) were successfully synthesized by simple electrochemical method using tetrabutyl ammonium bromide (TBAB) as a stabilizer in different polar protic solvents viz. water, ethanol and their mixture. XRD and Raman scattering analysis indicate the formation of pure hexagonal phase ZnO in pure ethanol as well as in water-ethanol mixture, while synthesis in pure water gives mixture of hexagonal ZnO and orthorhombic Zn(OH) 2 . FE-SEM micrographs show that ethanol as an electrolytic medium yields globular cluster of nanospheres, while involvement of water as an electrolyte gives spindle shaped cluster of quasi-spherical NPs. Band gap value of the ZnO NPs synthesized in ethanol was found to be higher, (3.65 eV) than those synthesized in water-ethanol mixture (3.50 eV) and pure water (3.35 eV). Significant enhancement in surface area was also observed with variation in the reaction medium from aqueous (45 m 2 g − 1 ) to alcoholic (160 m 2 g − 1 ). Sample synthesized in ethanol hence showed highest photo-degradation of methylene blue (MB) dye. The rate constant value for this sample was higher (0.0793 min − 1 ) than the values for sample synthesized in water-ethanol mixture (0.0242 min − 1 ) and pure water (0.0139 min − 1 ). The possible mechanism of formation of ZnO NPs as well as degradation of MB is proposed. [ABSTRACT FROM AUTHOR]