Magnetic porous PtNi/SiO2 nanofibers for catalytic hydrogenation of p-nitrophenol

In this work, the mesoporous SiO₂ nanofibers from pyrolyzing precursor of electrospun nanofibers were employed as support to immobilize PtNi nanocatalyst (PtNi/SiO₂ nanofibers). AFM, XRD, SEM, TEM, XPS, ICP-AES and N₂ adsorption/desorption analysis were applied to systematically investigate the morphology and microstructure of as-prepared products. Results showed that PtNi alloy nanoparticles with average diameter of 18.7 nm were formed and could be homogeneously supported on the surface of porous SiO₂ nanofiber, which further indicated that the SiO₂ nanofibers with well-developed porous structure, large specific surface area, and roughened surface was a benefit for the support of PtNi alloy nanoparticles. The PtNi/SiO₂ nanofibers catalyst exhibited an excellent catalytic activity towards the reduction of p-nitrophenol, and the catalyst's kinetic parameter (k_n = 434 × 10⁻³ mmol s⁻¹ g⁻¹) was much higher than those of Ni/SiO₂ nanofibers (18 × 10⁻³ mmol s⁻¹ g⁻¹), Pt/SiO₂ nanofibers (55 × 10⁻³ mmol s⁻¹ g⁻¹) and previous reported PtNi catalysts. The catalyst could be easily recycled from heterogeneous reaction system based on its good magnetic properties (the Ms value of 11.48 emu g⁻¹). In addition, PtNi/SiO₂ nanofibers also showed an excellent stability and the conversion rate of p-nitrophenol still could maintain 94.2% after the eighth using cycle.