Core–Shell Ag@Fe ₂ O ₃ /Reduced Graphene Oxide Nanohybrid for Supercapacitors

Despite having superior theoretical electrochemical properties such as high conductivity, high capacitance, and multivalent redox couples, Ag and Fe 2 O 3 in their bare form suffer from declining performance due to high volumetric strain and the formation of an unstable passivation layer. To address these issues, these materials are designed as a nanocore–shell composite with Ag as the core and Fe 2 O 3 as the shell. Such an architecture is synthesized via a simple hydrothermal technique and later anchored to rGO, which provides a high electrochemical surface area and structural strength for supercapacitor applications. It reaches a specific capacitance of 977 F g –1 in three-electrode systems and achieves high energy and power density of 45 Wh kg –1 and 533 W kg –1 @1 A g –1, respectively, in a full-cell device. The strong redox peak in the CV suggests that the core–shell structure reduces volumetric strain, thereby improving redox kinetics compared to those of bare materials. The redox-active Fe 2 O 3 shell is involved in charge transfer, with the highly conductive Ag core acting as a mediator to facilitate rapid charge transfer to the current collector without parasitic mechanisms, as indicated by a low charge transfer resistance. Thus, the electrochemical properties of Ag@Fe 2 O 3 /rGO prove their practical feasibility as promising electrodes for supercapacitor applications.