Visible light driven Z-scheme α-MnO2 (1D)/Bi7O9I3 (2D) heterojunction photocatalyst for efficient degradation of bisphenol A in water

Abstract

Z-scheme heterojunctions are gaining attention for their outstanding photocatalytic performance in degrading organic pollutants due to improved charge separation efficiency. In view of this, the present study is focused on the synthesis of novel 3D α-MnO2/Bi7O9I3 (MB) nanocomposites heterojunctions of varying α-MnO2 contents via facile in-situ chemical precipitation method at room temperature. Under optimum conditions, MB4 (comprising 485 mg of α-MnO2) exhibited exceptional performance, achieving about 97.5% of bisphenol A (BPA) degradation in 80 mins with a degradation rate constant of 0.08354 min−1. Such superior performance is attributed to efficient interfacial integration and charge separation, validated through various characterization techniques. Further, MB4 heterojunction facilitated Z-scheme electron-hole pair transfer and exhibited an augmented specific surface area. The active species involved in the degradation of BPA were identified as •O2– and •OH in scavenging experiments and supported by findings based on EPR. Additionally, degradation pathways and plausible BPA intermediates have been proposed based on LC-MS/MS studies. Furthermore, with an impressive mineralization rate (89.5%), the toxicity study unveiled less harmful intermediates than the parent compound BPA. MB4 photocatalyst also exhibited commendable stability, as evidenced by its studies based on five reuse cycles with 92.9% efficiency. In essence, visible-light-driven Z-scheme α-MnO2/Bi7O9I3 heterojunction photocatalyst offered a simple and sustainable approach for producing environmentally friendly materials, underscoring its potential in the removal of BPA in water and wastewater treatment.