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Eliminating harmful organic pollutants from contaminated water remains an urgent problem to be solved. Taking Rhodamine B (RhB) as a representative organic water pollutant we sought to design a facile and scalable synthesis of a BiFeO3/CeVO4 (BFO/CVO) nanocomposite catalyst for the degradation of organic pollutant under visible light. BFO nanorods and CVO nanoparticles were fabricated using single-step hydrothermal routes and the resulting materials could be easily combined using a simple wet-chemical precipitation method. From the morphological studies, pure BiFeO3 and CeVO4 revealed the 1D-nanorod and 0D-nanoparticles, respectively. For the BFO/CVO composite, 0D-nanoparticles were well attached on the 1D-nanorods of BiFeO3. Also, the 10 % BFO/CVO composite provided efficient photodegradation efficiency (92 %) of RhB with 0.0225 min−1 rate constant. Furthermore, the obtained photocatalyst had a low band gap energy value (2.01 eV) and photoluminescence intensity when compared to pure BFO and CVO under visible light illumination. The radical scavenging experiments proposed that the •OH acted a substantial role in the RhB decomposition pathway. The optimized BFO/CVO composite photocatalyst exhibits superior recyclability and photostability. The superior photocatalytic action of the 10 % BFO/CVO composite could be explained by the development of a heterojunction among BFO and CVO where electrons can migrate at the BFO/CVO interface. These results imply that BiFeO3/CeVO4 composites are suitable photocatalysts for the elimination of organic toxins from water.

Metal-organic frameworks (MOFs) are a significant class of porous, crystalline materials composed of metal ions (clusters) and organic ligands. The potential use of copper MOF (Cu-BTC) for the sonophotocatalytic degradation of Tetracycline (TC) antibiotic was investigated in this study. To enhance its catalytic efficiency, S-scheme heterojunction was created by combining Cu-BTC with Zinc tungstate (ZnWO4), employing an ultrasound-assisted hydrothermal method. The results demonstrated that the Cu-BTC/ZnWO4 heterojunction exhibited complete removal of TC within 60 min under simultaneous irradiation of visible light and ultrasound. Interestingly, the sonophotocatalytic degradation of TC using the Cu-BTC/ZnWO4 heterojunction showed superior efficiency (with a synergy index of ∼0.70) compared to individual sonocatalytic and photocatalytic degradation processes using the same heterojunction. This enhancement in sonophotocatalytic activity can be attributed to the formation of an S-scheme heterojunction between Cu-BTC and ZnWO4. Within this heterojunction, electrons migrated from Cu-BTC to ZnWO4, facilitated by the interface between the two materials. Under visible light irradiation, the built-in electric field, band edge bending, and coulomb interaction synergistically inhibited the recombination of electron-hole pairs. Consequently, the accumulated electrons in Cu-BTC and holes in ZnWO4 actively participated in the redox reactions, generating free radicals that effectively attacked the TC molecules. This study offers valuable perspectives on the application of a newly developed S-scheme heterojunction photocatalyst, demonstrating its effectiveness in efficiently eliminating diverse recalcitrant pollutants via sonophotocatalytic degradation.

We report on the fabrication of lysozyme microspheres (LyMs) incorporated with gold nanorods (NRs) as a distinctive approach for the encapsulation and release of an anticancer drug, 5-Fluorouracil (5-FU). LyMs with an average size of 4.0 ± 1.0 µm were prepared by a sonochemical method and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The LyMs were examined using hydrophobic (nile red) as well as hydrophilic (trypan blue) dyes under confocal laser scanning microscopy (CLSM) to obtain information about the preferential distribution of fluorescent molecules. Notably, the fluorescent molecules were accumulated in the inner lining of LyMs as the core was occupied with air. The encapsulation efficiency of 5-FU for LyMs-NR was found to be ∼64%. The drug release from control LyMs as well as LyMs incorporated with NRs was investigated under the influence of ultrasound (US) at 200 kHz. The total release for control LyMs and LyMs incorporated with gold NRs was found to be ∼70 and 95% after 1 h, respectively. The density difference caused by NR incorporation on the shell played a key role in rupturing the LyMs-NR under US irradiation. Furthermore, 5-FU loaded LyMs-NR exhibited excellent anti-cancer activity against the THP-1 cell line (∼90% cell death) when irradiated with US of 200 kHz. The enhanced anti-cancer activity of LyMs-NR was caused by the transfer of released 5-FU molecules from bulk to the interior of the cell via temporary pores formed on the surface of cancer cells, i.e., sonoporation. Thus, LyMs-NR demonstrated here has a high potential for use as carriers in the field of drug delivery, bio-imaging and therapy.