Architecture of ytterbium selenite nanorods: unlocking structural, optical, magnetic and electrochemical behaviour with boosting performance for supercapacitors

Ytterbium selenite (Yb₂Se₃O₉) was successfully synthesized using a simple coprecipitation technique, resulting in bamboo-like nanorods approximately 110 nm in size. The compound crystallizes in a monoclinic structure and exhibits promising features for optoelectronic applications and UV filtering. Spectroscopic analysis reveals native point defects as well as Schottky and Frankel surface defects, which facilitate radiative electron-hole recombination making it a potential material for display technologies. Ytterbium is embedded within an oxide matrix in the sample, and a distinct magnetic phase transition occurs between 20 K and 30 K under an applied magnetic field. At room temperature 300 K, the M-H curve indicates weak ferromagnetic behaviour. Electrochemical evaluation of Yb₂Se₃O₉ based electrodes in both symmetric and asymmetric supercapacitor configurations revealed impressive performance. The symmetric device exhibited a specific capacitance of 142.51 F g^-1, an energy density of 11.98 W h kg^-1, and a power density of 550 W kg^-1 at 1 A g^-1, with 78.09% capacitance retention after 10 000 cycles. Remarkably, the asymmetric supercapacitor achieved a higher specific capacitance of 169.86 F g^-1, an energy density of 60.39 W h kg^-1, and a power density of 800 W kg^-1 within a 1.60 V potential window, retaining 85% of its capacitance after 10 000 cycles. Impedance spectroscopy confirmed the material's double-layer capacitive behaviour. Overall, the asymmetric configuration demonstrated superior performance, making Yb₂Se₃O₉ a promising candidate for energy storage and conversion technologies.