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 Fe2O3 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 Fe2O3 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 Fe2O3 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@Fe2O3/rGO prove their practical feasibility as promising electrodes for supercapacitor applications.