Hydroxylation and sodium intercalation on g-C3N4 for photocatalytic removal of gaseous formaldehyde

• Published in: Carbon (New York) Vol. 175; pp. 467 - 477
• Main Authors: Hu, Chechia, Tsai, Wei-Fan, Wei, Wei-Han, Andrew Lin, Kun-Yi, Liu, Miao-Ting, Nakagawa, Keizo
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 30.04.2021; Elsevier BV
• Subjects: Adsorption; Carbon nitride; Electron transfer; Formaldehyde; g-C3N4; HCHO; Hydrogen bonds; Hydroxyl group; Hydroxylation; Intercalation; Na intercalation; Oxidation; Photocatalysis; Sodium; g-C3N4; Hydroxyl group; Na intercalation; HCHO; Photocatalysis
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2021.01.112

In this study, hydroxyl-modified/Na-intercalated g-C3N4 was used as an effective material for the removal of gaseous formaldehyde (HCHO) through adsorption and photocatalytic oxidation. In a simple reflux reaction using different NaOH concentrations, the surface-grafted hydroxyl (‒OH) groups of g-C3N4 formed internal hydrogen bonds with gaseous HCHO, while the Na atoms intercalated into the layered structure of g-C3N4 to create an electron transfer path (layer‒Na‒layer) to improve charge separation for photocatalytic oxidation. The hydroxylation as well as Na intercalation of g-C3N4 significantly increased its HCHO removal efficiency compared with that of bare g-C3N4. The HCHO removal capacity of the modified g-C3N4 reached approximately 0.12 ppm g−1 min−1, which was twice that of bare g-C3N4 (<0.06 ppm g−1 min−1). Moreover, the modified g-C3N4 was reused at least thrice without any decline in activity. This work provides a facile, simple, and fast approach to the modification of g-C3N4 via hydroxylation and Na intercalation to enhance HCHO adsorption as well as electron transfer, rendering it a promising material for indoor HCHO removal. [Display omitted] •Hydroxyl-modified and Na-intercalated g-C3N4 was prepared via treatment with NaOH.•Hydroxylation of g-C3N4 significantly improved HCHO adsorption.•Na intercalation in g-C3N4 created an electron transfer path for charge migration.•Hydroxyl-modified and Na-intercalated g-C3N4 exhibited high HCHO removal performance.