In this paper, we investigate the use of an iron-oxides photoactive coating to perform visible-light induced hydroxylation reactions, both for the photocatalytic degradation of azo-dyes pollutants and for the photosynthesis of guaiacol, a pharmaceutical and industrial intermediate for the synthesis of vanillin. A hierarchical micro/nano structured iron-oxides thin film was fabricated by pulsed laser deposition as the heterogeneous catalyst platform. A fluorescence assay based on coumarin/hydroxycoumarin conversion revealed the ability of the film to generate hydroxyl radicals in photo-Fenton-like mode. The process was then employed for the photocatalytic degradation of methyl-orange (MO) and acid orange 7 (AO7), with yields of 80% and 90% in 4 h irradiation respectively; in both cases hydroxylated intermediates were revealed by ESI-MS. When the substrate was switched to anisole, the hydroxylation process resulted in the accumulation of guaiacol, providing a proof-of-concept for heterogeneous photosynthesis. Investigation on H2O2 concentration, solvent and oxygen presence effects provided insights into optimization routes. These results, obtained with visible light and non-hazardous, scalable materials and reaction conditions, pave the way for the industrial application of photosynthetic methods.

An immobilized iron-oxides catalytic platform for photocatalysis and photosynthesis: Visible light induced hydroxylation reactions

Alessandra Molinari
Secondo
;
Martina Milani;
2022

Abstract

In this paper, we investigate the use of an iron-oxides photoactive coating to perform visible-light induced hydroxylation reactions, both for the photocatalytic degradation of azo-dyes pollutants and for the photosynthesis of guaiacol, a pharmaceutical and industrial intermediate for the synthesis of vanillin. A hierarchical micro/nano structured iron-oxides thin film was fabricated by pulsed laser deposition as the heterogeneous catalyst platform. A fluorescence assay based on coumarin/hydroxycoumarin conversion revealed the ability of the film to generate hydroxyl radicals in photo-Fenton-like mode. The process was then employed for the photocatalytic degradation of methyl-orange (MO) and acid orange 7 (AO7), with yields of 80% and 90% in 4 h irradiation respectively; in both cases hydroxylated intermediates were revealed by ESI-MS. When the substrate was switched to anisole, the hydroxylation process resulted in the accumulation of guaiacol, providing a proof-of-concept for heterogeneous photosynthesis. Investigation on H2O2 concentration, solvent and oxygen presence effects provided insights into optimization routes. These results, obtained with visible light and non-hazardous, scalable materials and reaction conditions, pave the way for the industrial application of photosynthetic methods.
2022
Chieregato, Filippo; Molinari, Alessandra; Milani, Martina; Fendrich, Murilo; Orlandi, Michele; Miotello, Antonio
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2493115
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