Functionalized carbon nanotube (FCNT) and Manganese Oxide (MnO₂) nanoflower hybrid material was synthesized using hydrothermal technique as a promising electrode material for supercapacitor applications. The morphological investigation revealed the formation of ‘nanoflower’ like structure of MnO₂ connected with FCNT, thus paving an easy path for the conduction of electrons during the electrochemical mechanism. A significant improvement in capacitance properties was observed in the hybrid material, in which carbon nanotube acts as a conducting cylindrical path, while the major role of MnO₂ was to store the charge, acting as an electrolyte reservoir leading to an overall improved electrochemical performance. The full cell electrochemical analysis of FCNT-MnO₂ hybrid using 3 M potassium hydroxide (KOH) electrolyte indicated a specific capacitance of 359.53 F g⁻¹, specific energy of 49.93 Wh kg⁻¹ and maximum specific power of 898.84 W kg⁻¹ at 5 mV s⁻¹. The results show promise for the future of supercapacitor development based on hybrid electrode materials, where high specific energy can be achieved along with high specific power and long cycle life.

High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of ${}^5{\mathrm{I}}_8\to {}^5{\mathrm{I}}_7$ transitions in ${\mathrm{Ho}}^{3+}$:${\mathrm{Y}}_2{\mathrm{SiO}}_5$ is reported. Crystal-field parameters determined for the two $C_1$ symmetry sites in ${\mathrm{Er}}^{3+}$:${\mathrm{Y}}_2{\mathrm{SiO}}_5$ are successfully used to model the Zeeman-hyperfine data, including the prediction of avoided crossings between hyperfine levels under the influence of an external magnetic field. The two six- and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.

Alkali‐activated functionalized carbon nanotubes (AFCNTs) and 2D nanostructured MoS₂ are investigated as a novel hybrid material for energy‐storage applications. The nanoflower‐like 2D MoS₂ is grown on the surface of AFCNT using the controlled one‐step hydrothermal technique. The activation of functionalized carbon nanotubes results in greater performance due to the improved surface area. The Brunauer–Emmett–Teller (BET) surface area of the AFCNTs is found to be 594.7 m² g⁻¹ which is almost 30 times of the as‐prepared carbon nanotubes (CNTs). The improved surface area with attached hydroxyl and carboxylic functional groups helps in the attachment of MoS₂ nanoflowers onto the AFCNT, thus reducing the interfacial resistance and providing an easy path for electron transfer. The electrochemical analysis shows a high specific capacitance of 516 F g⁻¹ at 0.5 A g⁻¹ with a corresponding energy density of 71.76 Wh kg⁻¹, which is an encouraging reported value from AFCNT and MoS₂ hybrid material. To the best of our knowledge, herein, the first report on AFCNTs and 2D MoS₂ nanostructured hybrid electrode material for supercapacitor applications is provided, and promising results in terms of specific capacitance, energy density, and power density by boosting the properties of individual material are explained.