Perovskite-type RCoO₃ (R = Pr, Eu, Gd) nanofibers for supercapacitor electrodes and antiferromagnet

Rare earth orthocobaltates nanofibers (PrCoO₃, EuCoO₃, and GdCoO₃) were prepared by a simple electrospinning method coupled with calcination. The PrCoO₃, EuCoO₃, and GdCoO₃ nanofibers have orthorhombic perovskite structure. The fabricated electrodes presented the typical pseudocapacitive characteristics, which originated from the reversible redox reactions of Co²⁺/Co³⁺ and Fe(CN)₆³⁻/Fe(CN)₆⁴⁻. At 1 A g⁻¹, the specific capacitances of the PrCoO₃, EuCoO₃, and GdCoO₃ nanofibers were 119, 133, and 196 F g⁻¹, respectively. The electrochemical characteristics of the PrCoO₃, EuCoO₃, and GdCoO₃ nanofibers exhibited favorable specific capacitance, good long-term cycling stability, and high coulombic efficiency, proving the possible application into energy storage devices. PrCoO₃ and EuCoO₃ nanofibers exhibited a magnetic state transition from paramagnetic to antiferromagnetic state. GdCoO₃ nanofibers showed a paramagnetic ordering at high temperature. The cooperation of the R³⁺ ions and the Co²⁺ ions contributed to the magnetism of rare earth orthocobaltates nanofibers. The antiferromagnetic behaviors of the fabricated samples confirm the potential application into spin-electronic devices.