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Cooperative and Fully Reversible Photocatalytic Colour Switching Activation in Graphene-Copper-TiO2 Nanoparticles

preprint
submitted on 24.02.2020, 16:36 and posted on 25.02.2020, 11:12 by David Maria Tobaldi, Luc Lajaunie, Dana Dvoranova, Bruno Figueiredo, Maria Paula Seabra, José Calvino, Vlasta Brezova, Joao Antonio Labrincha

Nanostructured systems showing reversible colour switching are envisaged to play a significant role in photo-switches, photo-optical sensors, smart windows, displays, optical storage memories. Most of the materials exhibiting reversible colour switching are organic compounds. However, their UV-light activation, low thermal and chemical stability, as well as harmful synthesis methods, are of limit for their extensive use. In this research, we have created an inorganic switchable photochromic material exploiting: (i) TiO2 ability of creating an exciton upon excitation, (ii) copper as the chromophore, and (iii) graphene’s extraordinarily high electron mobility. Our material showed itself to be able to work under visible-light, its photochromic property being three times faster than conventional titania based photochromic materials, reaching a stable change in colouration after only 30 mins of visible-light irradiation (versus > 120 min in conventional Cu-TiO2). With the addition of just 1 wt% graphene, the material exhibited a staggeringly stable photochromic switching over repeated cycles. These results relate to the best previously reported values for any form of TiO2-based photochromic material. This is therefore an excellent candidate for smart self-cleaning windows, and other chromic devices and applications.

Funding

FCT/484/15/01/2019/S

UIDB/50011/2020

UIDP/50011/2020

History

Email Address of Submitting Author

davidtobaldi@gmail.com

Institution

University of Aveiro

Country

Portugal

ORCID For Submitting Author

0000-0002-0112-8570

Declaration of Conflict of Interest

None

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