Published online by Cambridge University Press: 20 February 2018
Herein, we report on the syntheses of ZnO nanoparticles using different precursors Zn(NO3)2•6H2O, Zn(CH3COO)2•2H2O, ZnCl2, and ZnSO4.H2O by a microwave assisted method. The different precursors resulted in different structural, optical and photocatalytic degradation of Rhodamine B dye. The nanoparticles resulted in rod-like and pseudo-spherical morphologies when the ZnO2•6H2O, (Zn(CH3COO)2•2H2O and ZnCl2 precursors were used, with the proportion of the spherical morphology in each photocatalyst varying in the order Zn(NO3)2•6H2O > Zn(CH3COO)2•2H2O > ZnCl2. The ZnSO4.H2O precursor yielded trapezium shaped particles that were agglomerated through oriented attachment. For photocatalytic degradation studies, the fastest degradation was achieved using the SNO3- photocatalyst, which degraded the dye in a period of 120 min, followed by SCH3COO- at 150 min, SCl- at 180 min and SSO42- managing to degrade only 15 % of the dye after 240 min. The difference in the activity was attributed to surface area differences, which followed the order SNO3- > SCH3COO- >SCl- > SSO42-, with the photocatalyst that had the highest surface area showing high degradation rates. The high degradation rate observed for the SNO3- photocatalyst was also attributed to the presence of a large number of spherical particles thereby having a larger proportion of the high energy [0001] and [000-1] faces known to be highly active.