The present study aims at supplying a more in-depth picture of the Environmentally Persistent Free Radicals (EPFRs) generation from phenol (PhOH) on ZnO/SiO2 systems, by exploring the properties of ZnO nanoparticles with different intrinsic defectivity grown on highly porous silica with spherical (ZnO/SiO2_S) and worm-like morphology (ZnO/SiO2_W). In detail, besides an extensive structural, morphological, and surface investigation, the occurrence of inequivalent defect centers in the samples was tracked by photoluminescence (PL) experiments, which unveiled, for ZnO/SiO2_W, intense blue emissions possibly involving radiative recombination from Zni excited levels to the valence band or to VZn levels. Electron Spin Resonance (ESR) spectra, corroborated these results and revealed a remarkably different behaviour of the samples in the EPFRs formation model reaction. In fact, upon PhOH contact, the ESR spectrum of ZnO/SiO2_S showed the exclusive presence of a weak isotropic signal ascribable to a PhenO• EPFR. Instead, for ZnO/SiO2_W, intense features associated to oxygen species in proximity of VO+, VZn‒ and (VZn‒)2‒ centers dominate the spectra, while a minor contribution of PhenO• radical can be discovered only by signals simulation. These outcomes definitively envisage a role of the intrinsic defectivity of ZnO NPs on the final yield and stability of EPFRs generation, with VO+ and VZn‒ defects possibly involved in dissociative adsorption or oxidation processes at the oxide surface. Although this work focuses on ZnO, it is expected to foster a critical re-examination and integration of important results on other metal oxide/silica systems already reported in the literature, offering the chance to better evaluate the dependence EPFRs generation on the oxide defects chemistry.
D'Arienzo, M., Mostoni, S., Crapanzano, R., Cepek, C., Di Credico, B., Fasoli, M., et al. (2019). Insight into the Influence of ZnO Defectivity on the Catalytic Generation of Environmentally Persistent Free Radicals (EPFRs) in ZnO/SiO2 Systems. JOURNAL OF PHYSICAL CHEMISTRY. C.
|Citazione:||D'Arienzo, M., Mostoni, S., Crapanzano, R., Cepek, C., Di Credico, B., Fasoli, M., et al. (2019). Insight into the Influence of ZnO Defectivity on the Catalytic Generation of Environmentally Persistent Free Radicals (EPFRs) in ZnO/SiO2 Systems. JOURNAL OF PHYSICAL CHEMISTRY. C.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Presenza di un coautore afferente ad Istituzioni straniere:||No|
|Titolo:||Insight into the Influence of ZnO Defectivity on the Catalytic Generation of Environmentally Persistent Free Radicals (EPFRs) in ZnO/SiO2 Systems|
|Autori:||D'Arienzo, M; Mostoni, S; Crapanzano, R; Cepek, C; Di Credico, B; Fasoli, M; Polizzi, S; Vedda, A; Villa, I; Scotti, R|
D'ARIENZO, MASSIMILIANO (Corresponding)
|Data di pubblicazione:||2019|
|Rivista:||JOURNAL OF PHYSICAL CHEMISTRY. C|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/acs.jpcc.9b06900|
|Appare nelle tipologie:||01 - Articolo su rivista|