Magnetically separable low Pt substituted Co nanoparticles: Investigation of structural, magnetic, and catalytic properties
By Kaya, Dogan; Isik, Hasan Huseyin; Isik, Ilknur Baldan; Adanur, Idris; Wang, Yitao; Akyol, Mustafa; Karadag, Faruk; Ekicibil, Ahmet
Published in Physica B: Condensed Matter
2022
Abstract
Developing multifunctional nanoparticles (NPs) for magnetic and catalytic purposes is crucial for controlling magnetic properties and reducing production costs. We synthesized Co and low Pt loaded CoPt NPs by the modified polyol process. Co and CoPt NPs exhibited coexist fcc and hcp phases which are confirmed with x-ray diffraction and Rietveld refinement analysis. Scanning electron microscopy images revealed the average size of the NPs smaller than 9 nm with a narrow distribution. An irreversible magnetization-temperature behavior of the particles is observed in the modes of zero-field cooled and field cooled with a strong ferromagnetic signal close to 350 K. The field-dependent magnetization up to ±5 T was investigated to determine coercive field (Hc), exchange bias (HE), saturation magnetization (Ms), remanent magnetization (Mr), and the ratio of remanent magnetization to saturation magnetization (Mr/Ms). There is a general decrease in magnetic values due to an increase of both the temperature and the Pt ratio in Co nanoparticles. When the Pt/Co ratio drops to 1%, the sample was measured with the highest Hc value of 648.5 Oe and Ms value of 100 emu/g at 5 K. On the contrary, increasing the concentration of Pt to 10% resulted in a reduction for the Ms value below 40 emu/g. Besides, cyclic voltammetry measurements showed apparent hydrogen reduction in the potential range of −0.91 V and −0.96 V (vs Ag/AgCl) and 10% Pt loaded CoPt NPs exhibits the highest activity after 10th cycles and increase the activity up to 15.80 mA cm−2 at −1.2 V due to the surfactant.