Stable single phases of samarium gallium oxide (Sm 3 Ga x O y ) nano semiconductor self-assembly for supercapacitor and photocatalytic applications.

A cutting-edge approach has been attempted in the present work to develop two stable phases of samarium gallium oxide as functional materials in the form of energy storage electrodes and photocatalysts. A novel samarium gallium oxide with two stable phases has been synthesized by the gel matrix method. Their crystallinity, phase purity, and surface morphology were studied using modern analytical instruments, viz. , XRD, Raman spectra, FESEM, TEM, XPS, and UV-visible spectra. The values of the band gap energy calculated using Tauc relation for Sm 3 Ga 5 O 12 and Sm 3 GaO 6 are 5.06 eV and 4.74 eV, respectively. The electrodes fabricated from Sm 3 Ga 5 O 12 and Sm 3 GaO 6 exhibit values of specific capacitances of 91.95 mA h g -1 and 103.89 mA h g -1 , respectively, at 1 A g -1 current density. Among the two stable phases, Sm 3 GaO 6 shows significant cycling stability with a capacitive retention of 82.65% over 5000 charge/discharge cycles. The prepared asymmetric supercapacitor with Sm 3 GaO 6 as an active material exhibits an improved energy and power density of 11.72 W h kg -1 and 312.5 W kg -1 , respectively, with a coulombic efficiency of 97.17% after 5000 cycles. The results obtained from photocatalytic studies infer that the methylene blue dye was efficiently degraded by Sm 3 Ga 5 O 12 and Sm 3 GaO 6 with 92% and 97%, respectively, within 120 min of light irradiation. Sm 3 GaO 6 functions as a better and more efficient photocatalyst for degrading methylene blue dye, with a higher efficiency and a higher degradation rate of 0.0273 min -1 . The results obtained from electrochemical and photocatalytic studies infer that both phases of samarium gallium oxide can be considered as potential materials for energy storage and environmental remediation applications.