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Enhancement in the rate of nitrate degradation on Au- and Ag-decorated TiO2 photocatalysts

Caswell, Thomas, Dlamini, Mbongiseni W., Miedziak, Peter J., Pattisson, Samuel, Davies, Philip R., Taylor, Stuart H. and Hutchings, Graham J. 2020. Enhancement in the rate of nitrate degradation on Au- and Ag-decorated TiO2 photocatalysts. Catalysis Science and Technology 10 (7) , pp. 2083-2091. 10.1039/C9CY02473E
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Abstract

The solar-driven reduction of nitrate to nitrogen has been studied in the presence of a formate hole scavenger, over a series of Au- and Ag-decorated TiO2 catalysts. In this study, the catalyst preparation protocol was found to influence the nitrate transformation in the order: incipient wetness impregnation > stabilizer-free sol immobilization > sol immobilization. However, the sequence of performing specific treatment steps such as drying, calcination and sieving had a less pronounced effect. Low-conversion conditions were utilized to study the photo-degradation of nitrate over a range of monometallic and bimetallic catalysts with metal concentrations in the range M = 0–1 wt% (M: Au, Ag, Pd, AuAg). Our findings demonstrate that selectively degrading nitrate to N2 over these co-catalysts is non-trivial and is metal content dependent. For Au-doped TiO2 catalysts, the highest activity was measured over 0.2 wt% Au/TiO2 while a higher metal loading of 0.4 wt% was required for the Ag/TiO2 photocatalyst. Product selectivity was also demonstrated to be dependent on metal and metal loading: approximately 22% nitrite selectivity was determined over a 0.1 wt% Ag-doped catalysts, however this product was not detected when utilising Au-doped catalysts. Total selectivity to dinitrogen was shown to be possible on both Au and Ag doped catalysts, and again this was dependent on the concentration of the metal (Ag > 0.3 wt%; 0.2 < Au ≥ 0.4 wt%).

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Publisher: Royal Society of Chemistry
ISSN: 2044-4753
Funders: EPSRC
Date of First Compliant Deposit: 13 March 2020
Date of Acceptance: 3 March 2020
Last Modified: 30 Jun 2020 14:25
URI: http://orca.cf.ac.uk/id/eprint/130395

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