###### Abstract
[7] reported on the structure and capacitance of electrical double layers (EDL) at the graphene-ionic liquid interface via molecular dynamics simulations. Using this model, the distribution and migration of ions on the non-rough and rough electrode surfaces with different charge densities were compared and analyzed. The capacitance vs. voltage characteristic curves of EDL were obtained and corroborated with the electrode surface morphology on the capacitance of the EDL. Based on the detailed simulation results, it is clear that alternate distributions of anions and cations in several consecutive layers in the EDL could plausibly obtain the decaying amplitude characteristics along the direction perpendicular to the charged/uncharged electrode surface. In this alternate configuration, while charging occurs, the anions--for example, [BF\({}_{4}\)]--have a greater migration of ions when compared to the layers of cations--for example, [EMIM]+--due to the smaller size and steric effects of the anions. Finally, whether positively or negatively charging, the rough surface electrode with effective contact area between ions and electrodes possesses larger capacitance values when compared to the non-rough surface electrodes. An electrochemical method involving the anodization of TiO\({}_{2}\) foils was used to prepare titanium oxide nano arrays (TiO\({}_{2}\)-NTAs) for the application of dye-sensitized solar cells (DSSC) by [PERSON] et al. [8]. The preparation of photoanodes for the DSSC was carried out with TiO\({}_{2}\)-NTAs coated on the Fluorinated Tin Oxide (FTO) glass substrate using the sonication of precursor mixtures followed by the doctor blade process. The coating of silver nanoparticles (Ag NPs) or carbon materials (CMs) on the TiO\({}_{2}\)-NTAs was achieved using wet-chemistry and chemical vapor deposition (CVD) techniques, respectively. This individual coating of Ag NPs or CMs on the TiO\({}_{2}\)-NTAs led to an increase in DSSC efficiency by 15%. However, it was reported by the authors that Ag NPs and CMs were simultaneously coated on the TiO\({}_{2}\)-NTAs, the DSSC efficiency doubled (30%) due to the coexistence and additive effects of two mechanistic phenomena--plasmonic interactions (due to the Ag NPs coating) and \(\pi\)-\(\pi\) conjugation (due to the CMs coating). Overall, the he design characteristics and material's performance of the EES was optimized so that it can serve as an adequate storage unit for practical applications in solar, wind, and other potential sources such as DSSC. Hydrogen Energy Storage: In order to fulfill the current demand of primary or secondary energy sources from non-fossil fuel options, hydrogen stands as the first candidate due its many advantages. Hydrogen as a lean burning fuel, has a higher energy content than carbon-based fuels, and, as the by-product of hydrogen is water vapor, it has no carbon footprint. Hydrogen is the lightest gas and can be generated by various primary sources such as solar, wind, etc., and utilized as a fuel in both residential and industrial sectors. However, its intermediate storage faces challenges due to its gravimetric and volumetric densities. There are at least three types of hydrogen storage--gaseous storage or underground H\({}_{2}\) storage, liquid hydrogen storage, and storage in metal/complex hydride or sorbent systems. Based on these classifications of hydrogen storage, in addition to hydrogen storage densities, other vital parameters such as thermodynamics, kinetics, cycle life, refilling time, toxicity, and safety must be considered for its full deployment as an alternative fuel. In this Special Issue, four papers focus on hydrogen storage for potential stationary or automotive fuel cell applications. [PERSON] et al. [9] reported the potential risk factors associated with underground hydrogen storage in depleted gas fields via hydrogeochemical modeling (HGCM).