Experimental and computational study of a solar-powered electrolysis system with a SEPIC converter for green hydrogen production

The study presents an integrated approach for sustainable hydrogen production by coupling a photovoltaic system with an alkaline electrolysis unit optimized for fluctuating solar conditions. The catalyst for the electrolysis system was NiCoMo-modified Ni foam, which was created using a two-stage galvanostatic procedure that involved Ni and Co deposition followed by Mo enrichment. Electrochemical tests such were used to verify the catalytic activity of alkaline electrolysis. The device produced 120.2 mL of hydrogen in 30 min at 3 V, with a Faradaic efficiency of around 93.6 %, showing suitable electrochemical efficiency. To ensure stable electrolysis operation, a SEPIC DC-DC converter was integrated into the system, managed by real-time maximum power point tracking algorithms-Particle Swarm Optimization, Genetic Algorithm, and Artificial Bee Colony-modeled using 2023 solar irradiance data from Adana, Turkey. The ABC algorithm demonstrated the fastest convergence performance. The SEPIC converter successfully stabilized the output voltage at 7.5 V despite daily and seasonal battery voltage variations, maintaining optimal catalyst operating conditions. In the theoretical part of the study, a Co and Mo-doped Ni surface was constructed, and water adsorption on the most stable surface was examined using Density Functional Theory (DFT). Computational examination of the electrical structure revealed that Mo atoms contribute significantly more to the alloy matrix than Ni and Co. DFT calculations found that the oxygen atom of the water molecule adsorbs on top of the Mo atom at an adsorption energy of -1.03 eV. Mo doping on the Ni(111) surface directly enhances the strength of water adsorption.