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Article

Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity

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Department of Chemistry, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
2
Department of Chemistry, Università degli Studi di Torino, Via Giuria 7, 10125 Torino, Italy
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Laboratory of Green Chemistry, School of Engineering Science, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli, Finland
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Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
5
Institute of Materials, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-IMX-LTP, Station 12, CH-1015 Lausanne, Switzerland
*
Author to whom correspondence should be addressed.
Surfaces 2020, 3(1), 11-25; https://doi.org/10.3390/surfaces3010002
Received: 18 November 2019 / Revised: 10 January 2020 / Accepted: 11 January 2020 / Published: 14 January 2020
(This article belongs to the Special Issue Surface Aspects of Semiconductor Photochemistry)
In the present study, we use commercial digitally printed ceramic tiles, functionnalized by AgNPs doped micro–TiO2, to investigate the mechanism of Ag in the continouos photocatalytic antibacterial activity. The novelty of the research lies in the attempt to understand the mechanism of Ag, supported on TiO2, able to exhibit the same antibacterial activity of a standard system containing Ag species, but here, totally embedded on the tile surface, and thus not free to move and damage the bacteria cell. UV/vis diffuse reflectance spectroscopy (DRS) of AgNPs–TiO2 tiles indicated an enhanced visible light response, wherein a new absorption band was produced around 18,000–20,000 cm−1 (i.e., in the 400–600 nm range) owing to the surface plasmon resonance (SPR) of AgNPs. The antibacterial photocatalytic experiments were conducted towards the inactivation of E. coli under solar light and indoor light. It was found that the degradation speed of E. coli in the presence of AgNPs–TiO2 tiles is solar light-intensity depending. This justifies the semiconductor behavior of the material. Furthermore, the AgNPs–TiO2 tiles exhibit a high ability for the inactivation of E. coli at a high load (104–107 colony-forming unit (CFU)/mL). Additionally, AgNPs–TiO2 tiles showed a remarkable antibacterial activity under indoor light, which confirms the good photocatalytic ability of such tiles. On the basis of the reactive oxygen species (ROS) quenching experiments, O2•− species and h+ were more reactive for the inactivation of E. coli rather than OH species. This is because of the different lifetime (bacteria are more likely oxidized by ROS with longer lifetime); in fact, O2•− and h+ exhibit a longer lifetime compared with OH species. The generation of H2O2 as the most stable ROS molecule was also suggested. View Full-Text
Keywords: continuous antibacterial activity; self-cleaning surface; AgNPs doped TiO2; indoor and outdoor photocatalysis; commercial photocatalytic ceramic tiles continuous antibacterial activity; self-cleaning surface; AgNPs doped TiO2; indoor and outdoor photocatalysis; commercial photocatalytic ceramic tiles
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MDPI and ACS Style

Bianchi, C.L.; Cerrato, G.; Bresolin, B.M.; Djellabi, R.; Rtimi, S. Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity. Surfaces 2020, 3, 11-25. https://doi.org/10.3390/surfaces3010002

AMA Style

Bianchi CL, Cerrato G, Bresolin BM, Djellabi R, Rtimi S. Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity. Surfaces. 2020; 3(1):11-25. https://doi.org/10.3390/surfaces3010002

Chicago/Turabian Style

Bianchi, Claudia Letizia, Giuseppina Cerrato, Bianca Maria Bresolin, Ridha Djellabi, and Sami Rtimi. 2020. "Digitally Printed AgNPs Doped TiO2 on Commercial Porcelain-Grès Tiles: Synergistic Effects and Continuous Photocatalytic Antibacterial Activity" Surfaces 3, no. 1: 11-25. https://doi.org/10.3390/surfaces3010002

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