Transition metal oxide aerogels are a fascinating class of compounds that have received considerable attention in the last decade owing to their unique and exceptional properties, including high porosity, large surface area, and ultralow density. In this study, α-Ni(OH)₂ aerogels and annealed NiO/Ni aerogels were used to design and fabricate a two-electrode supercapacitor device. The physicochemical properties of the as-synthesized aerogels were characterized through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, the Brunauer–Emmett–Teller theory, and X-ray photoelectron spectroscopy studies. The annealed NiO/Ni aerogels showed a (specific capacitance of 1060 F/g) specific capacity of 422 C/g at 1 A/g current density and with good cycling stability (up to 10,000 cycles). The supercapacitor also demonstrated an energy density of 32.4 Wh/kg and power density of 1800 W/kg at a current density of 2 A/g. The specific capacitance of NiO/Ni aerogels was more than twice that of the α-Ni(OH)₂ aerogels. The practical applications of the aerogel were demonstrated by fabricating a two-electrode device.

Mixed-oxide transition-metal aerogels (AGLs), particularly manganese-based AGLs, have attracted considerable interest over the past decade owing to their extraordinary properties, including high porosity, good surface area, and ultralow density. To develop easy and lightweight materials for the ever-increasing energy storage demands of the near future, we designed a novel Mn-based electrode material to meet these rising requirements. MnO/Mn₂O₃ AGLs were synthesized using a novel borohydride hydrolysis method and then annealed at 200, 400, and 550 °C. The as-synthesized AGLs yielded flower-like network structures, but their porosity increased with increasing temperatures, to a high temperature of 400 °C. This increased porosity and network structure facilitate a high capacitance. A supercapacitor (SC) constructed with the three-electrode material yielded 230 F/g for the Mn_AGL@400 sample, followed by yields from the Mn_AGL@200 and Mn_AGL@550 electrodes. Furthermore, the device constructed with Mn_AGL@400 exhibited an energy density of 9.8 Wh/kg and a power density of ~16,500 W/kg at a current density of 20 A/g. The real-time applicability of the AGL was demonstrated by engineering a two-electrode device employing Mn_AGL@400 as the positive electrode, which exhibited 97% capacity retention and 109% Coulombic efficiency over 20,000 cycles.

In the past few years, metal chalcogenides have received extensive consideration because of their excellent physicochemical belongings. Particularly, molybdenum selenide (MoSe₂) is a promising metal dichalcogenide which possesses decent optical, electrical, and chemical properties and can be explored for a variety of applications. MoSe₂ has been extensively used for several applications such as energy storage and sensing. Since the energy crisis is one of the major challenges of today’s world, super-capacitors and hydrogen evolution are promising energy technologies that may benefit the global world in the future. Thus, researchers have been motivated towards the strategy and fabrication of electrode materials for super-capacitors and hydrogen evolution applications. MoSe₂ is a multifunctional material, and previous years have witnessed the rapid growth in the publication of MoSe₂-based electrode materials for super-capacitors, hydrogen evolution, and electrochemical sensing applications. Thus, it is of great significance to merge the previous reports into a single review article on MoSe₂-based modified electrode materials for super-capacitors, hydrogen evolution, and electrochemical sensing applications. Therefore, we have compiled the previous reports on the design and fabrication of MoSe₂ and electrodes based on its composites for super-capacitors, hydrogen evolution, and electrochemical sensing applications. It is believed that this article may benefit the researchers working in the research field of super-capacitors, hydrogen evolution, and electrochemical sensing applications.