Identification of Active Species in Photodegradation of Aqueous Imidacloprid over g-C3N4/TiO2 Nanocomposites

Abstract

In this work, g-C3N4/TiO2 composites were fabricated through a hydrothermal method for the efficient photocatalytic degradation of imidacloprid (IMI) pesticide. The composites were fabricated at varying loading of sonochemically exfoliated g-C3N4 (denoted as CNS). Complementary characterization results indicate that the heterojunction between the CNS and TiO2 formed. Among the composites, the 0.5CNS/TiO2 material gave the highest photocatalytic activity (93% IMI removal efficiency) under UV-Vis light irradiation, which was 2.2 times over the pristine g-C3N4. The high photocatalytic activity of the g-C3N4/TiO2 composites could be ascribed to the band gap energy reduction and suppression of photo-induced charge carrier recombination on both TiO2 and CNS surfaces. In addition, it was found that the active species involved in the photodegradation process are OH and holes, and a possible mechanism was proposed. The g-C3N4/TiO2 photocatalysts exhibited stable photocatalytic performance after regeneration, which shows that g-C3N4/TiO2 is a promising material for the photodegradation of imidacloprid pesticide in wastewater.

TiO2/graphitic carbon nitride nanosheet composite with enhanced sensitivity to atmospheric water

“…All are typical of g-C 3 N 4 (JCPDS 87-1526) with two prominent peaks at ∼27.5°and 13.0°due to the stacking of the graphitic carbon nitride sheet and the constituting aromatic tri-s-triazine unit. 1,2 The broad reections indicate the small number of coherent length along the c-direction (i.e., thickness of the stacked sheets) due to the HNO 3 -assisted thermal exfoliation. 2 The lack of any TiO 2 reections in the composite suggests that the metal oxide must be extremely small.…”

“…1,2 The broad reections indicate the small number of coherent length along the c-direction (i.e., thickness of the stacked sheets) due to the HNO 3 -assisted thermal exfoliation. 2 The lack of any TiO 2 reections in the composite suggests that the metal oxide must be extremely small. Fig.…”

“…where t is the thickness in cm of the pellet (i.e., the distance between electrodes), and A is the area of the pellet in cm 2 . Table 1 summarizes the calculated r and the resistance R LF in bracket.…”

“…1 Moreover, stacks of graphitic layers can be separated into carbon nitride nanosheets (CNNS) by a facile thermal exfoliation. 2 These nanosheets can be further modied by compositing with metals 3,4 or metal oxides, 5 leading to potential applications in photocatalysis, 2,6,7 thermal catalysis, 4 optical sensing, 8 nanocomposites, 9 to name but a few.…”

“…Specically, TiO 2 /CNNS composite is widely studied for organic disinfection in water because the heterojunction tailors band structure and charge separation. 2,26,27 In this regard, water adsorption on surface is an important microscopic process in e.g., photocatalysis, sensors, and separation membranes. 28 The sensitivity to atmospheric water leads to such applications, but it also complicates fundamental understanding of charge transport.…”