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Abstract_Suresh PILLAI
Semiconductor-based photocatalytic nanoparticles that exhibit antimicrobial activity under ordinary light (typically wavelengths greater than 400 nm) are highly desirable for building material applications. These materials offer a sustainable and energy-efficient approach to surface sterilisation.1,2 As part of the ongoing NATO-supported research project, we focused on developing functional surface coatings; our studies have primarily aimed at designing high-temperature stable antibacterial photocatalytic nanoparticles. The objective is to engineer coatings that retain their photocatalytic efficacy even after exposure to high temperature processing conditions, ensuring their practical applicability in industrial manufacturing. Among various photocatalytic materials, titanium dioxide (TiO₂) in its anatase phase is widely recognised for its superior photocatalytic activity and antimicrobial properties. However, a critical challenge in its application for high-temperature processed materials arises from its irreversible phase transformation to rutile. Under normal conditions, the anatase phase of TiO₂ undergoes a transition to the rutile phase within the temperature range of 500–600°C. This phase change significantly reduces its photocatalytic efficiency, thereby limiting its utility in high-temperature industrial processes, such as the production of ceramic tiles and sanitaryware. For many proposed commercial applications, including self-cleaning and antibacterial coatings for bathroom tiles and sanitaryware, maintaining the anatase phase at elevated temperatures is crucial. To address this limitation, our research explores the development of high-temperature stable, photocatalytically active, and antimicrobial materials by modifying the bandgap of TiO₂ through strategic doping with elements such as nitrogen (N), fluorine (F), sulfur (S), and carbon (C). These dopants play a critical role in tuning the electronic structure of TiO₂, extending its light absorption into the visible range while enhancing its thermal stability. The effects of different dopants on the structural and antimicrobial properties, with a focus on their potential for real-world applications in sustainable, self-cleaning, and hygienic building materials, will be discussed.
References
1. Swagata Banerjee, Suresh C. Pillai, Polycarpos Falaras, Kevin E. O’shea, John A. Byrne, and Dionysios D. Dionysiou. "New insights into the mechanism of visible light photocatalysis. The journal of physical chemistry letters 5, no. 15 (2014): 2543-2554.
2. CiaraByrne, Priyanka Ganguly, Maria Barbara Maccioni, Michael Nolan, Daphne Hermosilla, Noemí Merayo, Ángeles Blanco, Steven Hinder, and Suresh C. Pillai. "Impact of Au on the transition temperature and photocatalytic activity of TiO2. Journal of Photochemistry and Photobiology A: Chemistry (2024): 115848.
Acknowledgements:
The authors would like to acknowledge the financial support from the project SPS-MYP G5868 of the NATO Science for Peace and Security (SPS) Programme.