Ionic liquids (ILs) are molten salts that are entirely composed of ions and have melting temperatures below 100 °C. When immobilized in polymeric matrices by sol–gel or chemical polymerization, they generate gels known as ion gels, ionogels, ionic gels, and so on, which may be used for a variety of electrochemical applications. One of the most significant research domains for IL-based gels is the energy industry, notably for energy storage and conversion devices, due to rising demand for clean, sustainable, and greener energy. Due to characteristics such as nonvolatility, high thermal stability, and strong ionic conductivity, IL-based gels appear to meet the stringent demands/criteria of these diverse application domains. This article focuses on the synthesis pathways of IL-based gel polymer electrolytes/organic gel electrolytes and their applications in batteries (Li-ion and beyond), fuel cells, and supercapacitors. Furthermore, the limitations and future possibilities of IL-based gels in the aforementioned application domains are discussed to support the speedy evolution of these materials in the appropriate applicable sectors.

The TTAB surfactant micelle formation in presence of PVA was detected by the evaluation of CMC from the conductivity plot against the concentration of surfactant. Micellar parameters, such as critical micelle concentration (CMC), the extent of counter ion binding (β), and thermodynamic properties (ΔG⁰_m, ΔH⁰_m and ΔS⁰_m) of PVA + TTAB systems have been estimated. Values of CMC of the PVA + TTAB mixed system was achieved and found to reduce with enhancing PVA concentrations which designate the survival of interactions between TTAB and PVA. The values of CMC were found to undergo an increase in the mixed solvents in comparison to the values obtained in aqueous media, which might be attributed to the reduction of the dielectric constant as well as water cohesive energy. The values of free energy of micellisation ( $\mathrm{\Delta }{G}_m^o$) are negative for the PVA + TTAB system, suggesting a spontaneous aggregation phenomenon. The negative values of $\mathrm{\Delta }{G}_m^o$ in H₂O and 9% (w/w) mixed solvents follow the order: $\mathrm{\Delta }{G}_m^o$ (H₂O) > $\mathrm{\Delta }{G}_m^o$ (water + AN) > $\mathrm{\Delta }{G}_m^o$ (water + DO) > $\mathrm{\Delta }{G}_m^o$ (water + DMF). The thermodynamic properties of transfer were also estimated for the move of PVA+ TTAB mixed system from water to aqua-organic mixture of solvents. GRAPHICAL ABSTRACT

The requirement of clean and sustainable energy technology continues to rise as the energy supply crisis and environmental concerns worsen. As a result, new sources of alternative, stable, cost-effective, clean energy generation and storage devices need to be developed immediately. Several emerging cathode-based energy conversion and storage technologies rely on either the oxygen reduction reaction (ORR) or the hydrogen evolution reaction (HER) as their primary routes. Lately, scientists have paid much attention to enhancing the ORR and HER reaction rate and storing energy effectively by fabricating low-cost, highly active, and long-lasting electrocatalysts. Traditional electrocatalysts have relied on platinum (Pt), but its expensive price, limited durability, low selectivity, and poor alcohol tolerance have prompted the exploration of more cost-effective and promising catalysts. Recent studies have shown that electrocatalysts based on elements other than the platinum group metals (Ni, Cu, Fe, Co, Mn, etc.) exhibit remarkable ORR and HER catalytic efficacy and stability. In addition, carbon-based materials including carbon nanotubes (CNTs), graphite, diamond, graphene, and other carbon allotropes with high ORR catalytic activity are becoming increasingly significant due to their low cost and absence of metals. This review delves into the expanding area of ORR and HER electrocatalysts, summarizing recent developments in the fields of non-precious metal-based electrocatalysts, carbon-based electrocatalysts, and heteroatom doped carbon materials, and discussing the difficulties and future prospects of potential Pt-group metal alternatives.

Electrochemical behavior of nickel chloride was investigated in aqueous and reverse micellar solutions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) on glassy carbon (GC) and copper electrodes by cyclic voltammetric measurements. The electrochemical reduction of nickel ion to metallic nickel has been found to occur with ease on a copper electrode in aqueous solution. Electrodeposition of nickel on a copper substrate was therefore performed from reverse micellar solutions of CTAB/1-butanol/water with different water content using coulometric method at a fixed potential below the reduction potential. Morphology and microstructure of the deposits were examined by scanning electron microscopy; while elemental characterization was carried out by energy dispersive X-ray spectroscopic method and X-ray diffraction technique. The variation in the composition of the reverse micellar solutions brings about changes in the size and distribution of reverse micelles as revealed by dynamic light scattering measurements and consequently influences the morphology of electrodeposited nickel. The mechanism of electrodepostion of nickel from reverse micellar solutions has been elucidated and the organized media have, for the first time, been established as a suitable one for electrodeposition of nickel with tunable microstructure and morphology through systematic variation of the composition of the reverse micellar solutions.