Enhanced Photocatalytic Performance of Silver Decorated Zinc Oxide Nanoparticles Grown on Silica Microparticles

Pure and Ag-decorated ZnO nanoparticles (NPs) were synthesized using a two stage of modified sol-gel technique on microsized substrates, namely sand particles in an effort to prevent agglomeration during photocatalytic reactions. It was found that ZnO NPs can be grown efficiently on sand particles with good adhesion due to the presence of nanosized pits and cracks on the sand surface. The photocatalytic activity of supported pure ZnO NPs was compared to that unsupported pure ZnO NPs of similar size based on the photodegradation of methylene blue (MB) under UV light irradiation. For pure ZnO NPs, the photodegradation rate constant, k recorded for supported sample was found to be 8.6 × 10−3 min−1, being twice the value of that unsupported sample. Meanwhile, the presence of Ag-content that decorated on ZnO NPs has shown gradual increase in rate constants of Ag/Zn ratios from 0.08 to 1.39. The two rate constant values, k1 and k2 have all been observed for each Ag-decorated samples, having k2 greater than that k1 in all such cases. This can be explained by the accelerated degradation activities at lower MB concentrations. In summary, the efficiency of growing pure and Ag-decorated ZnO NPs on sand particles have therefore enhanced the photodegradation capabilities over pure ZnO which due to the prevention of agglomeration in the supported samples.