Escherichia coli-assisted synthesis of AgFeO₂ nanoparticles for antimicrobial, photocatalytic and hydrogen generation applications

The nanoparticles produced by physical and chemical methods are toxic in one or other way. Green chemistry is an emerging, stable and eco-friendly approach for biological production of nanomaterials. In the present study, Escherichia coli bacterium was utilized for the synthesis of silver iron oxide (AgFeO₂) nanoparticles by using precursors of two different salts; iron nitrate (Fe(No₃)₃ and silver nitrate (AgNO₃). Synthesized nanoparticles were characterized by EDX, XRD and SEM. AgFeO₂ nanoparticles, members of delafossite family were appraised for bacterial inactivation, photocatalytic degradation of toxic dyes and hydrogen generation through methanolysis. Delafossites are chemically stable compounds with high conductivity and decomposition temperatures (800–925 °C). The antimicrobial activity of AgFeO₂ nanoparticles was checked by well diffusion method against ATTC cultures of Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. Synthesized AgFeO₂ nanoparticles were employed for the degradation of Cango red and maximum degradation of 87 % was accomplished with 20 ppm (50 mL) solution of Cango red and 0.10 g AgFeO₂ as catalyst and reasonable hydrogen generating potential was also exhibited by the synthesized nanoparticles. As model fungi, Aspergillus niger and Mucor piriformis, are both significantly inhibited by AgFeO₂ NPs, while M. piriformis is the target of the compound's greater antifungal action.