Crystal Plane Impact of ZnFe2O4-Ag Nanoparticles Influencing Photocatalytical and Antibacterial Properties: Experimental and Theoretical Studies.

This paper describes the crystal interphase impact of ZnFe2O4-Ag in the photodegradation of Rhodamine B. Prepared ZnFe2O4 nanoparticles (NPs) were deposited with Ag NPs to offer ZnFe2O4-Ag (0-2.5%). An X-ray diffraction peak corresponding to the Ag NPs was detected if the particle content reached about 2.0%, observing multiple crystalline interphases in HR-TEM. Magnetic saturation (Ms) was increased ∼160% times for ZnFe2O4-Ag (7.25 to 18.71 emu/g) and ZnFe2O4 (9.62 to 25.09 emu/g) if the temperature is lowered from 298 to 5.0 K; while for Fe3O4 (91.09 to 96.19 emu/g), the Ms increment was just about 5.6%. After analyzing the DFT-Density of State, a decrease of bandgap energy for ZnFe2O4-Ag6 from the influence of the size of Ag cluster was seen. Quantum yield (Φ) was 0.60 for ZnFe2O4, 0.25 for ZnFe2O4-Ag (1.0%), 0.70 for ZnFe2O4-Ag (1.5%), 0.66 for ZnFe2O4-Ag (2.0%), and 0.66 for ZnFe2O4-Ag (2.5%), showing that the disposition of Ag NPs (1.5-2.5%) increases the Φ to >0.60. The samples were used to photo-oxidize RhB under visible light assisted by photopowered Langmuir adsorption. The degradation follows first-order kinetics (k = 5.5 × 10-3 min-1), resulting in a greater k = 2.0 × 10-3 min-1 for ZnFe2O4-Ag than for ZnFe2O4 (or Fe3O4, k = 1.1 × 10-3 min-1). DFT-total energy was used to analyze the intermediates formed from the RhB oxidation. Finally, the ZnFe2O4-Ag exhibits good antibacterial behavior because of the presence of Zn and the Ag components.

Determination of the surface temperature of magnetically heated nanoparticles using a catalytic approach.

Herein we describe a new method for the determination of the surface temperature of magnetically heated nanoparticles in solution using the temperature dependency of the catalytic performances of iron carbide nanoparticles coated with ruthenium (Fe2.2C@Ru) for acetophenone hydrodeoxygenation. A correlation between nanoparticle surface temperature and magnetic field could be established. Very high surface temperatures could be estimated in different solvents, which were also found similar at a given magnetic field and well above some solvent boiling points.