Efficient Photocatalytic Degradation of Ibuprofen from Aquatic Waste Using a Microwave Synthesized MoS2@Cs3Bi2Br9 Nanocomposite

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 MoS2@Cs3Bi2Br9 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 Cs3Bi2Br9) 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 Cs3Bi2Br9 to MoS2 (-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% H2O2), the 5% MoS2@Cs3Bi2Br9 composite achieved 96.77% degradation efficiency within 3 h, outperforming individual catalysts (61% for MoS2-sol-gel, 76% for MoS2-microwave, and 69% for Cs3Bi2Br9). The staggered energy bands of the heterojunction facilitate electron transfer from Cs3Bi2Br9 to MoS2 and hole migration in the reverse direction, suppressing recombination and amplifying hydroxyl radical (•OH) generation. Low-dose H2O2 (0.1%) acted as an electron scavenger to boost •OH production, while excess H2O2 (1%) promoted recombination, reducing the efficiency. The composite exhibited exceptional reusability, retaining >90% activity over five cycles via H2O2-assisted regeneration. This work underscores the potential of MoS2@Cs3Bi2Br9 as a sustainable, high-performance photocatalyst for degrading pharmaceutical pollutants, offering a viable strategy to mitigate emerging contaminants in water systems.