Sulfonic grafted graphitic-like carbon nitride for the improved photocatalytic production of benzaldehyde in water

This work reports the modification of graphitic carbon nitride (CN) through sulfonation (SCN) as an enhanced strategy for photocatalytic activity during the oxidation of benzyl alcohol to benzaldehyde. CN was prepared from melamine and functionalized with -SO3H groups using different doses of chlorosulfonic acid. The textural, structural, morphological, chemical, and optical properties of the prepared samples were characterized by diverse techniques. The increase in the doping dose produced, a decrease in surface area, a blue-shifted absorption edge under irradiation, and a decrease in the recombination charges. The -SO3H improved the kinetics of benzyl alcohol oxidation (BA) in aqueous solution and raised the selectivity to benzaldehyde (BD). An optimum dosage of precursor led to an SCN sample with the highest removal rate and selectivity. This optimized sample was selected for the study of the reactive oxidant species involved during the photocatalytic process, suggesting that the species with the highest contribution during BA oxidation was the superoxide radical, especially in terms of selectivity for the aldehyde formation. This work examples the modification of carbon nitride to enhance the production of an aldehyde with interest in the industry under a sustainable scheme that involves the transformation of light into chemical energy in aqueous solution.