Composition-tuned Au-Ag bimetallic cluster-modified TiO 2 films as efficient self-cleaning surfaces under visible light Vana Chinnappa Chinnabathini 1,2 , Fons Dingenen 2 , Rituraj Bora 2 , Zviadi Zarkua 1 , Peter Lievens 1 , Didier Grandjean 1 , Sammy W. Verbruggen 2 , and Ewald Janssens 1 1 Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Belgium, 2 Sustainable Energy, Air & Water Technology (DuEL), University of Antwerp, Belgium Surface modification of titanium dioxide photocatalysts with plasmonic metal nanoalloys is a promising way to extend the operation window to the visible light region, corresponding to the maximum output range of the sun’s total irradiance spectrum. 1 These photocatalysts are tested for the degradation of stearic acid (SA) since it is a widely applied method for assessing the photocatalytic activity of self-cleaning materials. SA is a good model compound for organic fouling on glass windows. 2 We studied the stearic acid degradation on TiO 2 decorated with 1.5-2.5 nm AuAg nanoalloy particles of different compositions both under UV and simulated solar light. Mono- and bimetallic Au x Ag 1-x (x=0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) clusters produced in a noble gas environment were soft-landed using cluster beam deposition (CBD) on TiO 2 P25-coated silicon wafers with a coverage of 4 atomic monolayer equivalents. While the photoactivity of the obtained films towards stearic acid degradation compared to pristine TiO 2 is basically unchanged under UV, a significant enhancement is observed under solar simulator with a very clear composition-dependent volcano-type trend peaking at the Au 0.3 Ag 0.7 composition.This behaviour may originate from their composition-dependent atomic arrangements and electronic structures stemming from their nucleation mechanism. 3,4 These results demonstrate the excellent potential of the CBD technology to fabricate novel and efficient noble metal modified photocatalytic surfaces with a high control over cluster coverage, and composition, without involving potentially hazardous chemical agents. References 1. W. Liao, S.W. Verbruggen, N. Claes, A. Yadav, D. Grandjean, S. Bals, P. Lievens, Nanomaterials 8 (2018) 30 2. W. Verbruggen, M. Keulemans, B. Goris, N. Blommaerts, S. Bals, J.A. Martens, S. Lenaerts, Applied Catalysis B: Environmental 188 (2016) 147-153 3. W. Liao, A. Yadav, K. Hu, J. van der Tol, S. Cosentino, F. D'Acapito, R.E. Palmer, C. Lenardi, R. Ferrando, D. Grandjean, P. Lievens, Nanoscale 10 (2018) 6684-6694 4. Mills, J.S.Wang, J . Photochem. Photobiol. A 182 (2006) 181-186.
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