Fluorescent carbon dot decorated MnO2 nanorods for complete photomineralization of phenol from water

Abstract

The enormous generation of wastewater has become the highest rated problem worldwide and day by day photocatalysis is gaining importance as the best option for wastewater treatment. In the context of recent studies for the development of photocatalysts, a novel MnO₂@CQDs nanocomposite (carbon dots decorated on MnO₂ nanorods) was prepared by a facile one-pot hydrothermal method. The optical properties revealed an excitation edge at 540 nm and a band gap of 1.3 eV for the nanocomposite. Structural and morphological studies revealed open-ended MnO₂ nanorods (length and breadth are 510 nm and 110 nm, respectively) and spherical CQDs are seen deposited on the surface of MnO₂. The nanocomposite also possesses a high surface area (95.3 m² g⁻¹) with mesopores (diameter 39 nm) which directly influences ionic transport. Using MnO₂@CQDs the photocatalytic degradation of phenol was tested under various operational parameters. Under optimum operational parameters, phenol degradation efficiency was found to be ∼90% with a high rate constant R = 0.029 min⁻¹. The mechanism for the higher activity of the MnO₂@CQDs nanocomposite was elucidated using different scavengers and cyclic voltammetry studies. These results underline the prospective application of the MnO₂@CQDs photocatalyst in water treatment.