Heterostructured graphitic carbon nitride/titanium dioxide for enhanced photodegradation of low-concentration formaldehyde under visible light

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Vol. 378; pp. 66 - 73
• Main Authors: Liu, Shou-Heng, Lin, Wei-Xing
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.06.2019; Elsevier BV
• Subjects: Absorption; Air purification; Anions; Carbon; Carbon nitride; Decomposition reactions; Diffuse reflectance spectroscopy; Electromagnetic absorption; Electron paramagnetic resonance; Electron spin; Electrons; Formaldehyde; Graphitic carbon nitride; Heterojunction; Heterojunctions; Holes (electron deficiencies); Indoor air purification; Indoor environments; Performance degradation; Performance enhancement; Photocatalysis; Photocatalysts; Photodecomposition; Photodegradation; Photoluminescence; Photons; Purification; Recombination; Spectroscopy; Spin resonance; Superoxide; TiO2; Titanium dioxide; Ultraviolet radiation; Ultraviolet reflection; Vapor phases; Visible-light-responsive; Indoor air purification; Visible-light-responsive; Graphitic carbon nitride; TiO2; Heterojunction
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2019.04.025

[Display omitted] •Synthesis of heterostructured TiO2 decorating g-C3N4 was done by using a simple calcination.•GCN/TiO2-3.0 shows higher visible-light activity of HCHO degradation than GCN and TiO2.•The superior activity may be due to the heterojunction between GCN and TiO2.•Photogenerated ·O2− and h+ are responsible for the visible-light-driven degradation of HCHO. In this study, a variety of heterostructured TiO2 decorating graphitic carbon nitride (denoted as GCN/TiO2-x) photocatalysts is synthesized by using a simple calcination method. Among the prepared GCN/TiO2-x, GCN/TiO2-3.0 composites possess the remarkably lower recombination rates of electron-hole pairs (evidenced by photoluminescence) and more visible-light absorption (evidenced by ultraviolet/visible diffuse reflectance spectroscopy) as compared to pure GCN and TiO2, respectively. Accordingly, the GCN/TiO2-3.0 photocatalysts show the enhanced performance toward degradation of low-concentration formaldehyde (HCHO) (rate constant = 0.0043 min−1) that is much better than GCN (rate constant = 0.0012 min−1) and TiO2 (rate constant = 0.0007 min−1) in the presence of visible light. This improvement observed for the photocatalytic degradation of gas phase HCHO can be probably caused by the heterojunction between GCN (the enhanced absorption of visible light) and TiO2 (improved separation of photogenerated electron-hole pairs). The electron spin resonance (ESR) signals suggest the photogenerated superoxide radical anions (·O2-) and hole (h+) may be responsible for the visible-light-driven photodecomposition of HCHO. This work provides a facile route to prepare efficient photocatalysts for indoor air purification by using interior lighting.