Bifunctional bimetallic PtNi, PtCu, and NiCu nanoparticles: Electrocatalytic activities for hydrogen evolution reaction and magnetic properties

Abstract

Pt-based materials are commonly used in sustainable energy technologies and fuel cells due to their catalytic ability. In this study, we synthesized bifunctional bimetallic PtNi, PtCu, and NiCu nanoparticles using the modified polyol method to investigate their catalytic for hydrogen evolution reactions (HER) and magnetic properties. X-ray diffraction and Rietveld refinement analyses revealed that all samples exhibited a face-centered cubic structure with a Fm3¯m space group. The chemical compositions of PtNi, PtCu, and NiCu bimetallic NPs were determined to be Pt28Ni72, Pt25Cu75, and Ni27Cu73, via stoichiometric calculations using the energy-dispersive X-ray spectroscopy data. The nanostructure and size were characterized by scanning electron microscopy, and the average particle size was found to be between 10 and 13 nm for all three catalysts with a narrow size distribution. The Pt28Ni72 catalyst exhibited the highest HER activity, with a minimum overpotential of −33 mV at −10 mA cm−2 and Tafel slopes with 55 mV dec-1 revealing the Volmer– Heyrovsky HER mechanism. The HER performance of the catalysts revealed that the highest HER activity is Pt28Ni72 > Pt25Cu75 > Ni27Cu73. The magnetic results revealed that the PtNi NPs exhibited a ferromagnetic to paramagnetic transition with a large coercive field of 628 Oe at 5 K. In this work, the addition of magnetic Ni in the structure resulted in multifunctional materials such as magnetically reusable bimetallic PtNi, PtCu, and NiCu catalysts with potential biomedical applications.