## 1 Introduction
In contrast, 6061-T6 and 7075-T6 Al alloys performed the worst, exhibiting low hydrogen flow rates, high energy consumption, and poor efficiency. Meanwhile, 1050-T0, 5052-T0, 7075-T0, and 7075-T7 Al alloys demonstrated moderate performance, making them viable alternatives for hydrogen production. [PERSON] et al. [14] examined the effects of KOH electrolyte concentration and electrode surface texture on HHO generator performance. Their findings revealed that increasing KOH concentration and modifying the electrode surface texture enhanced performance by expanding the electrode surface area. Similarly, [PERSON] et al. [13] reported that elevating the electrolysis temperature had the most significant impact on improving hydrogen production efficiency, followed by increasing the electrode surface area. In contrast, altering the electrode material had the least effect on efficiency enhancement. [PERSON] et al. [5] examined the effect of electrode spacing on hydrogen production. Their study found that reducing the distance between immersed electrodes enhanced the electrochemical reaction rate, increased hydrogen production, and improved efficiency. Although extensive research exists on water electrolysis, limited studies explore the relationship between electrode material, manufacturing processes, and efficiency. Therefore, a more comprehensive investigation is required to bridge this knowledge gap and better understand the influence of material processing and structure on gas production efficiency. Efficient hydrogen storage remains a critical challenge in advancing the hydrogen economy. Hydrogen can be stored in three primary forms: compressed gaseous hydrogen (GH\({}_{2}\)), liquid hydrogen (LH\({}_{2}\)), and cryo-compressed hydrogen (CcH\({}_{2}\)), each with distinct characteristics [3,13,15,16]. Compressed Gaseous Hydrogen (GH\({}_{2}\)): Stored at room temperature under extremely high pressures (up to 700 bar). While lightweight, it requires large storage volumes and has low energy density, with up to 10% energy loss during compression. Liquid Hydrogen (LH\({}_{2}\)): Stored at cryogenic temperatures (\(-240\) to \(-253\)\({}^{\circ}\)C) and low pressures (\(\sim\)10 bar). It offers higher energy density but demands strict insulation and consumes up to 40% of energy during liquefaction. Cryo-compressed Hydrogen (CcH\({}_{2}\)): Stored at cryogenic temperatures (\(-196\) to \(-240\)\({}^{\circ}\)C) and moderate pressures (150-350 bar). This method combines the advantages of GH\({}_{2}\) and LH\({}_{2}\), offering greater efficiency and flexibility [6]. Hydrogen can be stored in four types of pressure vessels (PVs). Type I: Fully metallic. Type II: A metallic liner reinforced with a fiber-resin composite along the hoop section. Type III: A metallic liner fully overwrapped with a fiber-resin composite. Type IV: A polymer liner entirely encased in composite material. While composite PVs offer superior performance, their high cost limits widespread adoption [3,6,13,15,16]. The design of PVs must consider operating conditions, lifespan, external loads, and potential failure modes when selecting materials [15]. Choosing the optimal storage method requires balancing cost and technical performance based on the specific application. Under high pressure, hydrogen adsorbs and dissolves on material surfaces, where atomic hydrogen diffuses into the material and interacts with lattice defects, leading to hydrogen embrittlement (HE)--a phenomenon that reduces ductility and toughness [3,6]. HE primarily affects metallic materials used in storage tanks under hydrogen exposure, potentially causing premature cracking and loss of mechanical properties due to stress corrosion cracking or hydrogen-induced cracking [6,16]. Both industry and academia have extensively studied HE mechanisms, alloy manufacturing, component assembly, and mechanical testing to improve material performance [3,15,16].