Fe3O4-Pt nanocomposite synthesized by green-hydrothermal hybrid method and its performance degrading methyl orange dye

• One-pot green hybrid synthesis of Fe 3 O 4 -Pt nanocomposite using coffee extract. • Ultra small nanocomposite with diameter between 2 and 5 nm. • Superparamagnetic nature of the nanocomposite is evidenced by magnetometry and Mössbauer spectroscopy. • Catalytic activity degrading methyl orange (MO) dye under UV irradiation. In this work is reported the one-pot synthesis of a Fe 3 O 4 -Pt nanocomposite with the use of coffee extract by a hydrothermal reaction. A direct mixture of FeCl 3 and PtCl 4 with a coffee extract concentration of 120 mg/mL in a stainless-steel autoclave reactor were heated for 18 h at 200 °C. Scanning and transmission electron microscopy show that Fe 3 O 4 -Pt nanocomposite have a mean size distribution of ∼ 5 nm for the Fe 3 O 4 nanoparticles with a partial coverage of small Pt 0 nanoparticles (less than 3 nm). Backscattered electron microscopy and infrared spectroscopy suggest the presence of an organic shell structure mediating the strong metal-support interaction. The magnetic behavior of the nanocomposite was studied by Mössbauer spectroscopy, also M(H) and M(T) measurements were made in a magnetometer; the measurements correspond to a superparamagnetic behavior. The photocatalytic activity of the Fe 3 O 4 -Pt nanocomposite was explored by degrading methyl orange dye after 10 min of UV irradiation. The results show the signified enhanced performance relative to Fe 3 O 4 nanoparticles and evidence its role as support for the Pt nanoparticles. The enhancement in the photocatalytic activity could be due to the synergy between Fe 3 O 4 , Pt and UV light via plasmon resonance promoting the electron − hole recombination rate.