## 1 Introduction  
Hydrogen is regarded as a key fuel for the future, with applications ranging from powering buildings and vehicles to serving as rocket fuel. As a clean energy carrier, it supports renewable energy sources and can be utilized in combustion engines or, more efficiently, in fuel cells to generate electricity for electric motors [1, 2, 3, 4, 5, 6, 7]. Additionally, hydrogen functions as an energy storage medium, allowing surplus electricity to be stored via electrolysis during off-peak hours, thereby minimizing energy waste [2, 3, 8, 9]. Recent technological advancements have improved hydrogen's feasibility, positioning it as a potential primary energy carrier in a sustainable future [3; 4; 8]. However, challenges persist in hydrogen production and storage, as different methods vary in cost and environmental impact. HHO gas, also known as Brown's gas or oxyhydrogen gas, is a mixture of hydrogen (H\({}_{2}\)) and oxygen (O\({}_{2}\)) in a 2:1 ratio, mirroring the composition of water (H\({}_{2}\)O). It is generated through water electrolysis, a process in which an electric current separates water into its constituent hydrogen and oxygen gases. Due to its higher flammability compared to diesel fuel, HHO gas can enhance combustion efficiency in diesel engines. The introduction of hydrogen increases the fuel's hydrogen-to-carbon (H/C) ratio, thereby reducing carbon-based emissions. Additionally, hydrogen exhibits an exceptionally high diffusion rate in air, which helps mitigate diesel fuel injection inhomogeneity and facilitates a more uniform fuel-air mixture [1]. According to [PERSON] et al. [1], the use of HHO gas in combination with biodiesel fuel in diesel engines has shown promising results. Studies consistently indicate that incorporating HHO gas enhances braking power, braking torque, and braking thermal efficiency while reducing brake-specific fuel consumption. Additionally, most researchers have observed that HHO gas lowers emissions of carbon monoxide (CO), unburned hydrocarbons (UHC), and particulate matter (PM), although it leads to an increase in nitrogen oxides (NOx) and carbon dioxide (CO\({}_{2}\)) emissions [1]. Therefore, integrating HHO gas into diesel engines presents a viable strategy for improving performance and reducing emissions in dual-fuel diesel engines without requiring modifications to the engine structure. As an emerging and sustainable energy source, HHO gas holds potential for enhancing energy security both now and in the future [1]. Water electrolysis is inherently slow, resulting in an overall electrolyzer efficiency of less than 40%. To make gas production more cost-effective and viable for a hydrogen-based economy, advancements are required to enhance system kinetics and reduce energy consumption [1; 4; 10; 11]. Research efforts focus on developing cost-effective electrode materials, minimizing the electrode gap, and improving overall system efficiency [2; 4; 5; 10; 11; 12; 13]. The influence of electrode materials on electrolyzer cost and efficiency remains under-explored [2; 4; 10; 12; 13]. Studies show that 316L stainless steel outperforms carbon steel in both hydrogen production and efficiency [12]. Nickel and stainless steel electrodes offer a cost-effective solution with favorable electrochemical properties. Additionally, polished electrodes generate gas at a higher rate than unpolished ones, as they have fewer oxide layers that would otherwise increase resistance and reduce active reaction sites, as highlighted by [PERSON] et al. [2]. Aluminum alloys, prone to oxidation, can serve as high-performing anodes for auxiliary hydrogen production systems in electrolyzers [10]. [PERSON] et al. [13] examined various aluminum alloy compositions and temper conditions as electrodes in an electrolyzer. Their study identified 6061-T0 Al alloy as the most efficient, offering the highest hydrogen flow rate, lower energy consumption, and superior process efficiency at a reasonable cost.