Facile fabrication of plasmonic Ag/ZIF-8: an efficient catalyst for investigation of antibacterial, haemolytic and photocatalytic degradation of antibiotics

Stabilization of Ni-containing Keggin-type polyoxometalates with variable oxidation states as novel catalysts for electrochemical water oxidation

The development of new recyclable and inexpensive electrochemically active species for water oxidation catalysis is the most crucial step for future utilization of renewables. Particularly, transition metal complexes containing internal multiple, cooperative metal centers to couple with redox catalysts in the inorganic Keggin-type polyoxometalate (POM) framework at high potential or under extreme pH conditions would be promising candidates. However, most reported Ni-containing POMs have been highly unstable towards hydrolytic decomposition, which precludes them from application as water oxidation catalysts (WOCs). Here, we have prepared new tri-Ni-containing POMs with variable oxidation states by charge tailored synthetic strategies for the first time and developed them as recyclable POMs for water oxidation catalysts. In addition, by implanting corresponding POM anions into the positively charged MIL-101(Cr) metal-organic framework (MOF), the entrapped Ni2+/Ni3+ species can show complete recyclability for water oxidation catalysis without encountering uncontrolled hydrolysis of the POM framework. As a result, a low onset potential of approximately 1.46 V vs. NHE for water oxidation with stable WOC performance is recorded. Based on this study, rational design and stabilization of other POM-electrocatalysts containing different multiple transition metal centres could be made possible.

Ag-loaded BiFeO3/CuS heterostructured based composite: an efficient photocatalyst for removal of antibiotics and antibacterial activities

The performance of advanced materials in environmental applications using green energy is the tremendous interest among researchers. The visible light responsive BiFeO3 (BFO), BiFeO3/CuS (BFOC), and Ag-loaded BiFeO3/CuS (Ag-BFOC) heterostructures have been synthesized by reflux method followed by hydrothermal and wetness impregnation method. These synthesized composites are well characterized through X-ray diffraction, UV diffuse reflectance spectroscopy, scanning electron microscope, and Fourier transfer infrared spectroscopy techniques. Compared with BFO and BFOC, Ag-BFOC exhibits the highest photocatalytic performance towards the degradation of antibiotics ciprofloxacin (76%) within 120-min time and also showed better antibacterial performance towards gram-negative (Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii) bacteria. Moreover, the novelty of the present work is the addition of CuS on the surface of BiFeO3 from heterojunction type II and facilitates the electron-hole channelization at the interfaces between BiFeO3 and CuS. Again, the loading of Ag on BiFeO3/CuS helps in shifting the absorption band towards the red end, is eligible to absorb more sunlight due to surface plasmon resonance effect, improves the separation efficiency of photo-generated charge carriers, and enhances the photocatalytic degradation of ciprofloxacin. The antibacterial property of Ag gives a best result towards antimicrobial activity. The prepared composites have proved their durability and stability by four successive cycles and prove the versatility of the composite.