1. Enhancement of ZnO Photocatalytic Activity by Incorporation of Silver Nanoparticles Acknowledgments RG thanks HEA for funding 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. Figure 1: Incorporation of silver facilitates electron trapping, with consequent reduction in emission intensity, which allows hole to oxidise water to produce hydroxyl radicals 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. 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. Figure 2: Experimental procedures carried out to synthesise and characterise Ag-ZnO and study its photocatalytic activity and mechanism of enhancement 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 Ag 2 O 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 Put in your name (underlined) and your supervisor (without titles along with other details. Title should be eye- catching and grab audience’s attention – this title effectively summarises the work. A schematic may more succinctly summarise the experimental details – just remember to have the extra details at hand 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) 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 Results should show trends where possible summarise key findings, with comment. Be prepared to discuss these results. Key references related directly to poster