Porous sponge-like AsOI/poly(2-aminobenzene-1-thiol) nanocomposite photocathode for hydrogen production from artificial and natural seawater

Abstract The direct conversion of seawater into hydrogen fuel represents a promising advancement in the pursuit of sustainable and renewable energy sources. In this study, we report the fabrication and characterization of a novel arsenic oxoiodide/poly(2-aminobenzene-1-thiol) (AsOI/P2ABT) nanocomposite photocathode with a distinctive sponge-like morphology. The composite exhibits hierarchical porosity with pore sizes ranging from ∼50 to 700 nm, along with a granulated surface uniformly decorated with ∼20 nm nanoparticles with a promising bandgap of 2.76 eV. The AsOI/P2ABT photocathode demonstrates significant potential for industrial-scale hydrogen generation by employing both natural and artificial seawater in a three-electrode photoelectrochemical cell. The system achieved hydrogen evolution rates of approximately 4.2 and 4.0 µmol/h cm² for artificial and natural seawater, respectively. Under full-spectrum white light illumination, the current densities in light ( J _ph ) reached −0.103 and −0.105 mA/cm², indicating comparable performance between the two electrolytes. These findings highlight the practicality of using natural seawater as a low-cost, abundant, and environmentally benign electrolyte. The study underscores the viability of the AsOI/P2ABT photocathode for direct seawater-to-hydrogen conversion, offering a scalable and eco-friendly approach to renewable hydrogen fuel production.