3.1 Synthesis and characterizations of Pd/Fe@N/C catalysts Figure showed some representative scanning electron microscopy (SEM) images and high-angle annular dark-field-STEM (HAADF-STEM) images of nitrogen-doped graphene encapsulated Pd/Fe@N/C catalyst. As shown in Figures and, the surface of the Pd/Fe@N/C catalyst had an obvious pore structure with the Pd and Fe particles dispersed evenly. The smaller Pd particles were evenly interspersed between the Fe particles, and the two particles were covered by a thin C shell to prevent the loss of the catalyst metal particles in the subsequent reaction. According to the HR-TEM analysis, the prepared N-doping Pd/Fe@N/C catalysts consisted of metal nanoparticles that were encapsulated by less than 5 graphene layers (Figure ), and >90% of metal species were encapsulated by a few graphene layers. The XRD spectrum showed that the graphitic carbon shell C (002) had a peak between 20 and 30, which confirmed that a thin graphene shell had been formed. Moreover, we could also observe the intensity peaks of Pd (011), Pd (011), N (002), and Fe3O4 species, which indicates the formation of N-doped Pd/Fe@N/C catalyst (Figure ). After the successful synthesis of the N-doped graphene encapsulated Pd and Fe bimetallic catalyst Pd/Fe@N/C, we then tested its catalytic reactivity for the reductive amination of nitrobenzene. room temperature (25°C), but only by raising the temperature to 40°C the selectivity can be increased to 91.34%, and the catalytic activity is also very large. The increase in degree is accompanied by a conversion rate of 92.60%. Similarly, during pressure screening, we found that many by-products are still generated at a hydrogen pressure of 0.1 bar. As shown in Figure (b), the overall conversion and selectivity are optimal at a hydrogen pressure of 0.8 bar. It is worth noting that the conversion rate of nitrobenzene at a pressure of 0.8 Mpa is higher than that at a pressure of 1 MPa. This is because competitive adsorption partly weakens the bond between each adsorbate and the surface.