Unveiling the synergistic role of anatase/brookite homojunctions in TiO2 mixed phases on the enhanced photocatalytic degradation of paracetamol under simulated solar light and the formation of CO2.- radical ion

Year: 2025

Authors: Blangetti N., Freyria FS., Manzoli M., Rivolo P., Piovano A., Darjazi H., Ditaranto N., Patrizi B., Doria S., Bonelli B.

Autors Affiliation: Politecn Torino, Dipartimento Sci Applicata & Tecnol, Corso Duca Abruzzi 24, I-10129 Turin, Italy; Politecn Torino, INSTM Unit Torino, Corso Duca Abruzzi 24, I-10129 Turin, Italy; Univ Turin, Ctr Nanostruct Interfaces & Surfaces, Dipartimento Sci & Tecnol Farmaco, Via P Giuria 9, I-10125 Turin, Italy; Univ Turin, Ctr Nanostruct Interfaces & Surfaces, NIS, Via P Giuria 9, I-10125 Turin, Italy; Politecn Torino, Dept Appl Sci & Technol DISAT, GAME Lab, Corso Duca Abruzzi 24, I-10129 Turin, Italy; INSTM, Natl Reference Ctr Electrochem Energy Storage, GISEL, Via G Giusti 9, I-50121 Florence, Italy; Univ Bari Aldo Moro, Dipartimento Chim, I-70125 Bari, Italy; CNR, Natl Res Council Italy, Natl Inst Opt, INO, Via Madonna Piano 10, I-50019 Sesto Fiorentino, FI, Italy; European Lab Non Linear Spect, LENS, Via Nello Carrara 1, I-50019 Sesto Fiorentino, FI, Italy; CNR, Inst Chem OrganoMetall Cpds, Natl Res Council Italy Via Madonna Piano, ICCOM, 10 Sesto Fiorentino, I-50019 Florence, Italy; Politecn Torino, Interdept Ctr PolitoBIOMed, Corso Duca Abruzzi 24, I-1012 9 Turin, Italy.

Abstract: Mixed-phase TiOQsystems offer unique opportunities for enhancing photocatalytic performance via interpolymorph junctions (homojunctions). While anatase/rutile interfaces have been extensively studied, anatase/ brookite junctions remain comparatively underexplored. Here, we demonstrate that homojunctions between anatase and brookite, formed via a template-free, pH-controlled synthesis and low-temperature calcination (200 degrees C), significantly enhance photocatalytic activity under simulated solar light. High-resolution TEM reveals direct anatase/brookite junctions without isolated brookite crystallites. At the same time, IR spectroscopy detects the formation of CO2.- radical ions, suggesting that the homojunctions act as active defect sites, potentially contributing to visible light absorption or increasing photocatalytic performance. Notably, the surface generation of CO2.- under mild conditions could open new perspectives for COQ activation and solar fuel production, while also positioning this species as a valuable intermediate in organic synthesis for the formation of carboxylic acids. Compared to an anatase/brookite/rutile system obtained through calcination at 600 degrees C, the sample calcined at low temperature exhibits superior performance in degrading paracetamol, a model emerging contaminant in city water. Importantly, Surface-Enhanced Raman Spectroscopy (SERS) enables direct identification of paracetamol degradation intermediates, revealing a mechanistic pathway similar to that promoted by a commercial anatase/ rutile TiO2. These findings underscore the potential of anatase/brookite homojunctions as efficient charge-separating interfaces, as further supported by electrochemical impedance spectroscopy.

Journal/Review: APPLIED SURFACE SCIENCE ADVANCES

Volume: 30      Pages from: 100896-1  to: 100896-18

More Information: This study was carried out within the << GREEN UP: GREENER NANOMATERIALS FOR UPCONVERSION IN PHOTOCATALYTIC AP-PLICATIONS >> project-funded by the Ministero dell’Universita e della Ricerca-within the PRIN 2022 program (D.D.104 -02/02/2022) funded by the European Union-Next Generation EU. This manuscriptreflects only the authors’ views and opinions and the Ministry cannot be considered responsible for them. F.S.F. acknowledges the LuSH Art project Luminescent Solar Heterostructures for Artificial photosynthesis (Marie Curie Action, European Union Horizon 2020 research and innovation program, grant agreement no 843439) for the initial part of this work. A.P. acknowledges the Italian Ministry for University and Research (MUR) for funding under the D.M. 1062/2021 program. H.D. acknowledges the Italian Ministry for University and Research (MUR) for funding under the National Recovery and Resilience Plan (PNRR Mission 4, Component 2, Investment 1.3-D.D. 1561 11.10.2022 of the Ministero dell’Universitae della Ricerca (MUR) , PE0000021) , within the NEST-Network 4 Energy Sustainable Transition. This manuscript reflects only the authors’ views and opinions, neither the European Union nor the European Commission can be considered responsible for them. N.B., F.S.F., P.R., A.P., H.D. and B.B acknowledge support under the MUR program Dipartimenti di Eccellenza 2023-2027 ’’ (CUPE17G22001490006) .
KeyWords: Homojunctions; Brookite; Solar photocatalysis; Emerging contaminants; CO2.-radical ion; Surface-Enhanced Raman Spectroscopy; TiO2 polymorphs
DOI: 10.1016/j.apsadv.2025.100896