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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. ORCID: https://orcid.org/0000-0003-4394-766X, Taylor, Stuart H. ORCID: https://orcid.org/0000-0002-1933-4874 and Hutchings, Graham J. ORCID: https://orcid.org/0000-0001-8885-1560 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 Nov 2022 12:49
URI: https://orca.cardiff.ac.uk/id/eprint/130395

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