## 1 Introduction  
Metallic nanoparticles such as platinum (Pt), silver (Ag), gold (Au), and palladium (Pd) have garnered significant attention due to their exceptional catalytic activity in diverse reactions [1, 2, 3, 4]. Nevertheless, the propensity of metal nanoparticles to undergo aggregation, thereby reducing their catalytic activity, remains a critical challenge for their practical applications in heterogeneous catalysis [5, 6]. The state-of-the-art strategy centers on immobilizing metal nanoparticles onto porous carbon matrices via covalent anchoring, which effectively mitigates aggregation while preserving accessible active sites for heterogeneous catalytic applications [7, 8, 9]. While magnetic supports exhibit unparalleled advantages in catalyst recovery via magnetic separation compared with conventional solid carriers [10], their propensity for oxidative dissolution under harsh reaction conditions remains a critical limitation that necessitates surface stabilization strategies. In recent years, carbon has emerged as a promising shell material for encapsulating magnetic cores, with its hierarchical porosity and high specific surface area enablingenhanced catalytic performance and structural stability [11; 12; 13; 14; 15; 16]. The integration of magnetic cores (e.g., Fe\({}_{3}\)O\({}_{4}\)) within carbon-encapsulated architectures not only imparts ferromagnetic responsiveness to the composite but also mitigates oxidative dissolution of the core through carbon shielding, while simultaneously offering abundant anchoring sites for nanocatalyst immobilization. In order to effectively stabilize metal nanoparticles, the shell material must act as a substrate with a hierarchically porous structure and superior dispersion properties. These structural features are essential for strengthening metal support electronic coupling and optimizing the catalytic activity of noble metal catalysts [17]. At present, there are two methods to synthesize core-shell Fe\({}_{3}\)O\({}_{4}\)@C. Firstly, magnetic Fe\({}_{3}\)O\({}_{4}\) nanospheres are synthesized and then wrapped in a heat treatment using carbon sources such as glucose, dopamine, and polymers. Although Fe\({}_{3}\)O\({}_{4}\)@C supports show good dispersion, the preparation method is time-consuming, and the steps are cumbersome [18; 19; 20; 21; 22; 23]. Therefore, one-step preparation of Fe\({}_{3}\)O\({}_{4}\)@C supports was investigated in detail, and the Fe\({}_{3}\)O\({}_{4}\)@C composite was further prepared through a solvothermal approach employing ferrocene as the iron and carbon source. However, the synthesis was conducted at a relatively elevated temperature of 220 \({}^{\circ}\)C and involved the use of acetone, a volatile solvent with a low boiling point, which poses safety concerns [24]. Meanwhile, loading precious metals into the carbon shell layer is a highly challenging research endeavor. Most current studies utilize the impregnation method. However, the catalysts obtained through this method exhibit rather poor dispersion of active components [25; 26]. It is still a great challenge to safely prepare the shell material with excellent dispersion of metal nanoparticles. Fe\({}_{3}\)O\({}_{4}\)@C core-shell nanospheres were synthesized via a one-pot hydrothermal method in this paper, followed by annealing under a nitrogen atmosphere. Subsequently, platinum (Pt) nanoparticles were uniformly deposited onto the carbon shell of Fe\({}_{3}\)O\({}_{4}\)@C through a solvothermal approach, using ethylene glycol as a reducing agent. The as-prepared Fe\({}_{3}\)O\({}_{4}\)@C-Pt composite was systematically characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM).