A simplistic preparation of gold-decorated magnetic hybrid nanoparticles as recyclable Nanocatalysts for the hydrogenation of Nitroarenes as well as surface-enhanced Raman scattering substrates

• Preparation of gold-doped magnetic hybrid nanoparticles based on the spontaneous oxidation-reduction/co-precipitation method is achieved. • The as-prepared hybrid nanoparticles can be used as nanocatalysts for the hydrogenation of various nitroarenes with remarkably high efficiency. • The hybrid nanoparticles were also capable of being surface-enhanced Raman scattering (SERS) substrates. The magnetic properties of the hybrid nanoparticles further increase their applicability. Magnetic nanomaterials have attracted significant attention for their multifunctional properties and ease of recovery. In this study, gold-decorated magnetic hybrid nanoparticles (AuMNPs) were synthesized through a simple and efficient spontaneous reduction-oxidation process. By controlling the initial precursor ratio, we successfully fabricated a hybrid nanostructure that balances magnetic properties with gold surface exposure. This synthesis approach simplifies the preparation process and avoids the use of toxic surfactants. The resulting AuMNPs were characterized using transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), zeta potential analysis, and X-ray spectroscopy. Owing to their magnetic properties, the AuMNPs function as quasi-homogeneous nanocatalysts that can be easily separated and reused. The catalytic performance was evaluated through the hydrogenation of o-nitroaniline (o-NA), achieving over 99% conversion within 3 minutes with an apparent rate constant (k app ) of 0.0392 s −1 , which represents a notably high conversion efficiency compared to many previously reported nanocatalysts. The experimental results also indicated that the conversion efficiency of AuMNPs was influenced by pH, temperature, and the catalyst loading. Furthermore, the AuMNPs demonstrated excellent durability, retaining high performance over 9 consecutive reaction cycles. Beyond catalysis, the AuMNPs also served as effective substrates for surface-enhanced Raman scattering (SERS), enabling sensitive detection of p-aminothiophenol (pATP) with a detection limit of 50 nM. Overall, the AuMNPs prepared via this facile route combine high catalytic activity, magnetic recyclability, and SERS sensitivity. These attributes enable their potential for industrial catalysis and analytical applications, as well as for fundamental studies on reaction mechanisms.