Enhancement of ZnO Photocatalytic Activity by Incorporation of Silver Nanoparticles

1. Enhancement of ZnO Photocatalytic Activity by Incorporation of Silver Nanoparticles Title should be eye-catching and grab audience’s attention – this title effectively summarises the work. Put in your name (underlined) and your supervisor (without titles along with other details. Reena George, Michael K Seery and Suresh C Pillai DT203/4 Forensic and Environmental Analysis School of Chemical and Pharmaceutical Sciences, DIT reenamoleg@gmail.com Introduction ZnO is a wide band gap semiconductor whose photocatalytic activity has been widely studied. This work reports a study of the incorporation of silver nanoparticles into the ZnO matrix with the aim of enhancing the photocatalytic activity. The mechanism is studied by monitoring the excitonic emission of ZnO. • Results and Discussion • XRD confirmed formation of nano-sized ZnO at T > 400 °C with no change in spectral shape on addition of Ag (Figure 3a) – indicating Ag depositing along grain boundaries. • DSC analysis showed formation of crystalline ZnO at 405 °C, and in the case of Ag-ZnO the decomposition of Ag2O at 395 °C (Figure 3b). IR and Raman spectra confirmed the formation of ZnO at T>400 °C (Figure 3c and 3d). Figure 3: (a) XRD of Ag-Zno; (b) DSC of Ag-ZnO, (c) IR of Ag-Zno at 80, 300 and 400 °C and (d) Raman spectrum of Ag-ZnO Figure 1: Incorporation of silver facilitates electron trapping, with consequent reduction in emission intensity, which allows hole to oxidise water to produce hydroxyl radicals • Emission intensity reduced on increasing Ag loading indicating electron trapping by silver (Figure 4a). Strong excitonic emission (390 nm) indicates good crystalline quality (cf. Raman) • Photocatalytic activity significantly increases on addition of silver, up to 5 mol%. Above this loading silver covers catalyst surface and provides recombination sites. (Figure 4b) Experimental Details 0 – 5 mol % Ag-ZnO was synthesised by adding increasing amounts of silver nitrate to an ethanolic solution (700 mL) of zinc acetate (10.98 g) and oxalic acid (12.55 g) at 60 °C. The sol was stirred for 2 h to give a gel, which was calcined at a range of temperatures from 300 – 1000 °C to give Ag-ZnO nanopowder. Results should show trends where possible summarise key findings, with comment. Be prepared to discuss these results. Figure 4: (a) Emission spectra of Ag-ZnO. (Inset: Stern-Volmer Plot) (b) variation in degradation rate consant of rhodamine 6g on increasing silver loading Acknowledgments RG thanks HEA for funding Key references related directly to poster A schematic may more succinctly summarise the experimental details – just remember to have the extra details at hand References M. J. Height, S. E. Pratsinis, O. Mekasuwandumrong, P. Praserthdam, Appl. Cat. B. Environmental, 2006, 63, 305. M K Seery, R George, P Floris, S C Pillai, J. Photchem. Photobiol. A. 2007,189 (2-3), 258. Figure 2: Experimental procedures carried out to synthesise and characterise Ag-ZnO and study its photocatalytic activity and mechanism of enhancement