Sodium thiosulfate modified graphitic carbon nitride for enhancing the photocatalytic production of aldehydes
Year: 2024
Type: article
Abstract: The oxidation of alcohols to aldehydes is one of the most relevant reactions in organic chemistry . The currently implemented methods based on expensive noble metallic catalysts , toxic solvents, and high temperature and pressure conditions have released the seek for softer and cheaper alternatives such as photocatalysis . In this sense, graphitic carbon nitride has been modified with sodium thiosulfate as a source of S and Na + incorporation in the structure, aimed at enhancing the photocatalytic performance on the oxidation of alcohols to aldehydes, i.e. cinnamaldehyde , benzaldehyde , and vanillin in aqueous solution. Three g-C 3 N 4 samples synthesized from different precursors, i.e. melamine , thiourea , and urea, were treated with sodium thiosulfate. Urea led to the g-C 3 N 4 with the highest mesoporosity (surface area, 69 m 2 g −1 ) and photocatalytic activity . The modification with 5 % (wt.) of Na 2 S 2 O 3 enhanced the pseudo-first order rate constant of cinnamyl alcohol oxidation from 0.265 h −1 (bare sample) to 0.792 h −1 (Na 2 S 2 O 3 -modified). The characterization of the material suggests a better charge separation of the photogenerated charges after S and Na + incorporation in the structure, minimizing the recombination rate of photogenerated charges. The optimum photocatalyst , tested in aqueous solution, was most selective in the production of benzaldehyde (selectivity, >100 %) > cinnamaldehyde (>23 %) > vanillin (∼5 %). The selectivity was considerably boosted under acetonitrile as the solvent medium, raising in the case of cinnamaldehyde the 23 % recorded in water to 51 % in pure acetonitrile . The degradation mechanism suggests a strong influence of the photogenerated holes and the superoxide radical , the latter being more selective in the oxidation of the alcohol.
Authors: M. Alejandra Quintana, Julia Aguirre, M. Ángeles Martín-Lara, Mónica Calero, Mario J. Muñoz-Batista, Rafael R. Solís
Institution: Universidad de Granada
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,760
OpenAlex ID: W4402629580