Highly porous network of tungsten (VI) oxide-iodide/polypyrrole nanocomposite photocathode for the green hydrogen generation

A novel and highly efficient tungsten (VI) oxide-iodide/polypyrrole nanocomposite (WO₂I₂/I-Ppy) photocathode has been successfully developed for the production of green hydrogen from the natural electrolyte source of Red SEA water. The fabrication of the WO₂I₂/Ppy nanocomposite photocathode is accomplished using cost-effective mass production methods. This involves the oxidation of pyrrole with iodine followed by a reaction with Na₂WO₄. Subsequently, the resulting nanocomposite WO₂I₂/Ppy showcases very fine quantum dot particles with an average size of 5 nm. The exceptional behavior of these nanoparticles holds promise for optical properties with a small bandgap of 2.6 eV, particularly in terms of photon trapping and absorbance. This characteristic contributes to the photocathode’s outstanding performance, as evidenced by a remarkable photocurrent density (J_ph) compared to the dark current density (J_o). Specifically, the observed values are − 0.12 mA cm⁻² for J_ph and − 0.05 mA cm⁻² for J_o, highlighting the substantial increase in current density under illumination. Photocurrent measurements at wavelengths of 340 and 440 nm further showcase the photocathode’s efficacy, registering values of 0.114 and 0.110 mA cm⁻², correspondingly. The hydrogen production rate achieved by this promising photocathode is significant, yielding 52 µmol/h 10 cm². This study is a promising step toward the economic application of the WO₂I₂/I-Ppy nanocomposite photocathode for green H₂ production.