SHARE - Thin-film photocatalysts implementing Z-ScHeme designs for solar treatment of antibiotics in water: addressing the rise of Antimicrobial REsistance

Solar photocatalysis has been investigated in the last decades as an advanced oxidation process for environmental remediation. This project comes to life in this area but focusing on materials with a Z-scheme design for the inactivation of antibiotic residues in water. This will avoid human exposure to potentially hazardous residues and mitigate the associated phenomenon of antimicrobial resistance (AMR), a top threat to public health, exacerbated by heavy antibiotic use due to the pandemic. Moreover, while treated wastewater reuse is considered attractive for agriculture (PNR 2021-2027), major concerns for contaminants such as antibiotics do exist. Concerning materials, three major challenges must be addressed: (1) cheap, scalable, non-hazardous photocatalysts, (2) compatible with sunlight yet highly efficient and stable, (3) operating in heterogeneous catalysis mode in flow-reactors.

We aim to solve these issues with a class of composites implementing Z-scheme designs in thin-films. Z-schemes, inspired by nature, inhibit the recombination of photogenerated electron-hole couples, thus enhancing their lifetime and boosting the yield of redox processes employing them. Z-schemes can be implemented in solid-state devices by using two semiconductors with opportunely aligned band edges. However, since both semiconductors need to be exposed to the redox substrates, simply layering the two materials is not a viable strategy. In this project, we will use a hierarchical structuring approach: a thin-layer of a semiconductor A (Fe and W oxides), with micro/nano features on the surface, will serve as support for smaller nanoparticles of a semiconductor B (g-C₃N₄ and CdS).

The resulting solid-state thin-film photocatalyst will provide critical advantages over the currently employed homogeneous or colloidal ones: it is inherently compatible with flow reactors with no need for post-processing. It will be characterized by X-ray Spectroscopies, including in working conditions, and by Time-resolved photoluminescence (PL), to investigate the efficiency of charge separation.

 Efficiency in the photocatalytic removal of selected antibiotics will be evaluated and the reaction mechanisms investigated by using spectroscopic and chromatographic methods, by-products identified, and their toxicity assessed. Finally, the system will be tested on real from a wastewater treatment plant (WWTP).