Iron-Doped MnO x /Graphene Oxide Nanoarchitectures with Three-Dimensional Conductive Networks for Printed Capacitive Microsensors

Manganese oxides are attractive electrode materials for microsupercapacitors, owing to their high theoretical capacitance and environmental benignity. However, their poor conductivity and structural instability severely limit practical applications. This work reports Fe-doped MnO x /graphene oxide (Fe-MnO x /GO) nanoarchitectures with three-dimensional conductive networks prepared via annealing-assisted self-assembly. The composite features a unique hybrid structure composed of both rod-like and spherical MnO x crystals. These crystals are interconnected by a graphene oxide matrix, forming efficient electron transport pathways. Concurrently, Fe 3+ doping introduces oxygen vacancies and Fe–O–Mn bonds, which enhance the electronic conductivity, stabilize the crystal lattice, and suppress Mn 2+ dissolution. The printed microelectrodes thus deliver a high areal capacitance of 26.1 mF cm –2, an energy density of 5.22 μWh cm –2, a maximum power density of 1.2 mW cm –2, excellent cycling stability, and