2.3. Preparation of Ag–Fe NPs

The phytogenic green synthesis of Ag–Fe bimetallic nanoparticles was carried out according to the previously reported protocol [25]. In this synthesis process, 25 mL of 2 mM AgNO₃ was mixed with 2 mM Fe(NO₃)₃ in a three-neck flask with constant stirring and room temperature (25 °C). After that, 25 mL of freshly prepared beetroot extract was added to the above-prepared metal precursor solution under constant stirring with a magnetic stirrer at 25 °C. The transformation of the reaction color recognized the synthesis of Ag–Fe nanoparticles—ruby red or purple. Finally, the Ag–Fe nanoparticles were separated by centrifugation of the colored solution for 30 min at a speed of 10,000 rpm. The acquired solid material was washed with distilled water and ethanol multiple times, followed by drying in a vacuum oven at 100 °C. The solid material was subsequently used for further characterizations and applications.