In situ synthesis of europium oxide (Eu2O3) nanoparticles in heteroatom doped carbon nanofibers for boosting the cycling stability of supercapacitors.

Maintaining a high specific energy without losing cycling stability is the focus of the supercapacitor field. In this study, carbon nanofibers including europium oxide nanoparticles (CNF/Eu2O3) have been synthesized in the presence of thiourea via a simple approach and applied for the first time as an electrode for SCs. The CNF/Eu2O3-1 electrode doped with nitrogen and sulfur heteroatoms possessed a favorable specific capacitance of 183.2 F g-1, a specific energy of 9.15 W h kg-1, and an excellent capacitance retention of 94.8% even after 10 000 cycles at 1 A g-1. Such excellent performance is ascribed to the surface functionalities, high surface area, and good interaction of Eu2O3 with CNFs. This strategy will provide guidance for other rare element-based electrodes in the field of energy storage.