Efficient Photocatalytic Degradation of Ibuprofen from Aquatic Waste Using a Microwave Synthesized MoS<sub>2</sub>@Cs<sub>3</sub>Bi<sub>2</sub>Br<sub>9</sub> Nanocomposite
Saima Jan, Ajit Sharma, Owais Hassan Wani, S. Islam, Shahid Ahmad Shah, Wengang Bi, Aadil Ahmad Bhat
Abstract
The persistent presence of pharmaceutical contaminants such as ibuprofen (IBF) in aquatic ecosystems poses significant environmental and health risks, as conventional wastewater treatments often fail to eliminate these recalcitrant compounds. Herein, a novel MoS 2 @Cs 3 Bi 2 Br 9 heterojunction photocatalyst was synthesized via sol–gel and microwave methods to address this challenge. Comprehensive characterization (XRD, FTIR, SEM, EDX, and UV–vis) confirmed the structure of composite and optical properties, revealing a reduced bandgap of 3.04 eV (vs pristine Cs 3 Bi 2 Br 9 ) due to a type II heterojunction with staggered band alignment. This configuration enabled efficient charge separation, as photogenerated electrons migrated from the conduction band (CB) of Cs 3 Bi 2 Br 9 to MoS 2 (−0.3 eV), while holes transferred inversely, suppressing recombination and enhancing the redox activity. Under optimized conditions (20 mg/L IBF, pH 6.0, visible light, 0.1% H 2 O 2 ), the 5% MoS 2 @Cs 3 Bi 2 Br 9 composite achieved 96.77% degradation efficiency within 3 h, outperforming individual catalysts (61% for MoS 2 -sol–gel, 76% for MoS 2 -microwave, and 69% for Cs 3 Bi 2 Br 9 ). The staggered energy bands of the heterojunction facilitate electron transfer from Cs 3 Bi 2 Br 9 to MoS 2 and hole migration in the reverse direction, suppressing recombination and amplifying hydroxyl radical (•OH) generation. Low-dose H 2 O 2 (0.1%) acted as an electron scavenger to boost •OH production, while excess H 2 O 2 (1%) promoted recombination, reducing the efficiency. The composite exhibited exceptional reusability, retaining >90% activity over five cycles via H 2 O 2 -assisted regeneration. This work underscores the potential of MoS 2 @Cs 3 Bi 2 Br 9 as a sustainable, high-performance photocatalyst for degrading pharmaceutical pollutants, offering a viable strategy to mitigate emerging contaminants in water systems.