Highly efficient photocatalytic degradation of naphthalene by Co3O4/Bi2O2CO3 under visible light: A novel p–n heterojunction nanocomposite with nanocrystals/lotus-leaf-like nanosheets structure

Abstract

Exploring visible-light-driven nanomaterials to substitute crucial bulk composite under UV-light is of great significance in photodegradation of hardly-decomposed persistent pollutants in the environment. Herein, the novel p–n heterojunction photocatalyst p-Co3O4/n-Bi2O2CO3 with zero dimensional(0D)-two dimensional(2D)nanocrystals/lotus-leaf-like nanosheets structure was successfully obtained for the first time via a facile hydrothermal method, in which the density of Co3O4 loaded on the Bi2O2CO3 was easily tuned by the concentration of Co3O4 precursor in the solution. The outstanding feature of the photocatalyst is that the resultant hybrid nanocomposite exemplified the p–n heterojunction visible-light materials for degrading the naphthalene efficiently and effectively. As the presence of Co3O4 and the synergistic interactions of p–n heterojunction, the recombination of photogenerated charge carriers has been suppressed, and the visible light absorbance has been improved. Consequently, the visible light photocatalytic performance has been enhanced. The p-Co3O4/n-Bi2O2CO3 sample with Co3O4/Bi2O2CO3 mass ratio 1:6 exhibited the highest photocatalytic activities among all the as-prepared samples with the degradation efficiency of about 91.02% naphthalene in 150 min. The photocatalytic mechanism of p-Co3O4/n- Bi2O2CO3 for degrading naphthalene was analyzed based on the semiconductor energy band theory and the formation of an internal electrostatic field. The probable degradation intermediates and products of naphthalene were identified by GCMS. The proposed photodegradation pathways of naphthalene were described by combining the frontier electron density calculation and GCMS results.