Cobalt-incorporated triclinic sodium aluminosilicate nanostructures: structural, optical, magnetic, and electrochemical investigations

Cobalt-doped sodium aluminosilicate nanostructures were synthesized via a sol–gel method and investigated for their structural, optical, magnetic, and electrochemical properties. X-ray diffraction confirmed the formation of a triclinic albite phase (NaAlSi₃O₈) with successful incorporation of Co²⁺ ions into the aluminosilicate framework. Optical absorption studies revealed new bands associated with tetrahedral Co²⁺ in Al₂O₃ nanocrystals, and a systematic decrease in the optical band gap with increasing Co content due to the creation of localized states in the band gap. Magnetic measurements demonstrated a transition from diamagnetic behavior in the undoped sample to ferromagnetic behavior in Co-doped samples, with enhanced saturation magnetization linked to exchange interactions. Electrochemical studies showed that the sample with the lowest Co content (ANSS1Co) exhibited the highest specific capacitance (187 F g⁻¹ at 1 A g⁻¹) and excellent cycling stability, retaining 89.5% capacitance after 8000 cycles. These results highlight the potential of Co-doped sodium aluminosilicate nanostructures as stable electrode materials for energy storage applications.