A bi-overlayer type plasmonic photocatalyst consisting of mesoporous Au/TiO 2 and CuO/SnO 2 films separately coated on FTO

• Published in: Physical chemistry chemical physics : PCCP Vol. 17; no. 27; pp. 18004 - 18010
• Main Authors: Naya, Shin-ichi, Kume, Takahiro, Okumura, Nozomi, Tada, Hiroaki
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/C5CP01111F

The principal purpose of this study is to present a new design for preparing highly active immobilized gold nanoparticle-based plasmonic photocatalysts. Gold nanoparticles were loaded on rutile TiO 2 particles with a mean size of 80 nm (Au/TiO 2 ) by the deposition precipitation method. The surface of SnO 2 particles with a mean size of 100 nm was modified by copper( ii ) oxide clusters (CuO/SnO 2 ) with the loading amount ( Γ /Cu ions nm −2 ) precisely controlled by the chemisorption–calcination cycle technique. Two mesoporous overlayers of Au/TiO 2 and CuO/SnO 2 were coated side by side on glass substrates with a fluorine-doped tin oxide film (FTO) using the doctor blade method (Au/mp-TiO 2 |FTO|CuO/mp-SnO 2 ). As test reactions for assessing the visible-light activity, we carried out gas-phase decomposition of acetaldehyde and liquid-phase oxidation of alcohol. In each reaction, this bi-overlayer type catalyst shows a high level of visible-light activity much exceeding those of Au/TiO 2 particles and a Au/mp-TiO 2 |FTO mono-overlayer type catalyst [ J. Phys. Chem. C , 2014, 118 , 26887]. To confirm the origin of the striking visible-light activity, we studied the electrocatalytic activity of CuO/mp-SnO 2 |FTO electrodes for the oxygen reduction reaction (ORR). Both the visible-light activity of Au/mp-TiO 2 |FTO|CuO/mp-SnO 2 and the electrocatalytic activity of CuO/mp-SnO 2 |FTO for ORR strongly depend on the Γ value. A good positive correlation has been found between the visible-light activities and the electrocatalytic activity for ORR. The striking activity of the present bi-overlayer type catalyst can be attributed to the efficient and long-range charge separation by the vectorial electron transport (Au(oxidation sites) → TiO 2 → FTO, SnO 2 → CuO(reduction sites)) and the excellent electrocatalytic activity of the CuO clusters.