In-situ stirring assisted hydrothermal synthesis of Bi2S3 nanowires on BiVO4 nanostructures for improving photocatalytic performances

A novel magnetic AgVO3/rGO/CuFe2O4 hybrid catalyst for efficient hydrogen evolution and photocatalytic degradation

A superior semiconductor material with efficient charge separation and easy reuse could be a promising route for efficient photocatalytic hydrogen evolution and pollutant degradation. AgVO₃ is one of the best visible light active materials which has attracted much attention for several biological and environmental applications. In the aim of enhancing its stability and recyclability a novel AgVO₃/rGO/CuFe₂O₄ heterojunction was prepared by hydrothermal method for hydrogen generation (H₂) and 4-nitrophenol (4-NP) degradation as well. The composite was well characterized by XRD, SEM, HR-TEM, XPS and VSM. The morphological images suggested the rod shaped AgVO₃ and irregular shaped CuFe₂O₄ are unevenly distributed on reduced graphene oxide (rGO) layers. The hydrogen evolution results indicated that the composite showed around 8.937 mmol g^-1h^-1 of H₂ generation which was ∼2.3 times and ∼9.2 times higher than pure AgVO₃ (3.895 mmol g^-1h^-1) and CuFe₂O₄ (0.96 mmol g^-1h^-1) respectively. The 4-NP degradation efficiency of the prepared composite was observed as 94.7% (k = 0.01841 min^-1) which is much higher than the AgVO₃ (66.3%) and CuFe₂O₄ (38.2%) after 4 h of irradiation. The higher efficiency could be attributed to the heterojunction formation and faster charge separation. The radical trapping results indicated that the •OH, O₂•- and photogenerated h⁺ are the main species responsible for efficient activity. The AgVO₃/rGO/CuFe₂O₄ heterojunction showed 49.6 emu/g of saturation magnetization and confirms that it could be easily separated with an external magnet, and showed 85.3% of degradation efficiency even after 6 recycles which indicated its higher stability and recyclability. Thus, our study provides new insight into hydrogen generation and phenol degradation using AgVO₃ based recyclable composites.

Starch-Assisted Synthesis of Bi2S3 Nanoparticles for Enhanced Dielectric and Antibacterial Applications

Starch [(C₆H₁₀O₅) _n ]-stabilized bismuth sulfide (Bi₂S₃) nanoparticles (NPs) were synthesized in a single-pot reaction using bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O) and sodium sulfide (Na₂S) as precursors. Bi₂S₃ NPs were stable over time and a wide band gap of 2.86 eV was observed. The capping of starch on the Bi₂S₃ NPs prevents them from agglomeration and provides regular uniform shapes. The synthesized Bi₂S₃ NPs were quasispherical, and the measured average particle size was ∼11 nm. The NPs are crystalline with an orthorhombic structure as determined by powder X-ray diffraction and transmission electron microscopy. The existence and interaction of starch on the NP's surface were analyzed using circular dichroism. Impedance spectroscopy was used to measure the electronic behavior of Bi₂S₃ NPs at various temperatures and frequencies. The dielectric measurements on the NPs show high dielectric polarizations. Furthermore, it was observed that the synthesized Bi₂S₃ NPs inhibited bacterial strains (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) and demonstrated substantial antibacterial activity.