Photoelectrochemical Hydrogen Generation from Seawater Using Modified g-C₃N₄/NiO Photo-electrode Heterojunction

This study investigates seawater splitting for hydrogen evolution via a photoelectrode-membrane assembly. A composite photoelectrode of nickel oxide (NiO) and iron-doped graphite carbon nitride (g-C₃N₄) was fabricated and characterized to determine its suitability for photocatalytic activity.  PVA-based membranes were integrated within the reactor to explore ion transport and selectivity in photoelectrochemical device (PEC) configurations. Fluorene–Thiophene–Triphenylamine–Coumarin (FTTC) molecular sensitizer when used in conjunction with a novel Fe/g-C₃N₄/NiO photoelectrode system, resulting in an increase in hydrogen production through solar energy from seawater. The seawater splitting experiments were conducted at various applied voltages, and the system's efficiency was evaluated based on the hydrogen evolution rate, current density, and stability when subjected to seawater. These advancements can be pivotal in decarbonizing maritime energy infrastructures and enabling distributed green hydrogen production in coastal regions. PVA membrane emerges as a promising candidate due to its high selectivity and durability, while the Fe-g-C₃N₄/NiO photoelectrode proves effective for solar-driven hydrogen generation in harsh saline environments. The membrane can reject Cl⁻ ions by more than 90% but it allows H⁺ and OH⁻ ions to pass with a conductivity of 10⁻³ S/cm, and this is the reason why, after 24 hours, only 15% of the photocurrent is lost, while in the case of no membrane, 50% decay occurs.