Conversion of Seawater to H ₂ Fuel Using a Promising Photocathode Based on Bismuth(III) Oxide Iodide–Poly(2‐Aminobenzene‐1‐Thiol) With Intercalated Iodide as a Multilayer Spherical Nanocomposite

This study focuses on the conversion of Red Sea water into hydrogen (H 2 ) fuel using a photoelectrochemical (PEC) approach. To achieve this, a photocathode was fabricated based on a bismuth (Bi)(III) oxide iodide–poly(2‐aminobenzene‐1‐thiol) (P2ABT) multilayer spherical nanocomposite with intercalated iodide (Bi oxyiodide [BiOI]/I–P2ABT MLS‐nanocomposite). The nanocomposite was characterized using XPS and XRD techniques to analyze its composition and structure, while FTIR provided detailed insights into its functional groups. Morphological and structural evaluations were performed using SEM, TEM, and cross‐sectional modeling, revealing a multilayer spherical structure with a diameter of 80 nm, a wall thickness of approximately 12 nm, and an interlayer spacing of 10 nm. The performance of the BiOI/I–P2ABT MLS‐nanocomposite photocathode was assessed in an electrochemical cell using both natural Red Sea water and artificially prepared seawater. Hydrogen production rates were determined, yielding 6.0 and 4.8 µmol h −1 cm −2 , with corresponding current densities ( J ph ) of −0.6 and −0.38 mA cm −2 , respectively. Additionally, the photocathode’s sensitivity was tested under varying photon wavelengths (340–730 nm), showing efficient photo response and variation in J ph values across the spectrum. The BiOI/I–P2ABT MLS‐nanocomposite offers significant advantages, including high efficiency, scalable synthesis, cost‐effectiveness, and ecofriendly green chemistry, making it a promising candidate for industrial applications. This work demonstrates the potential of this innovative photocathode for the direct conversion of seawater into hydrogen fuel. The research team aims to advance this technology further by developing a prototype photocathode for large‐scale hydrogen production directly from seawater.