Fabrication of a Photocathode Based on Silver Iodide/Poly-2-Aminothiophenol with High Optical Absorbance Related to Intercalated Iodide Ions for Hydrogen Generation from Wastewater Without a Sacrificial Agent

The use of sewage water as an electrolyte, without any additional sacrificial agent, for hydrogen (H₂) gas generation represents a compelling avenue for converting waste into sustainable energy. In this study, a promising photocathode is developed, leveraging materials with high photon absorbance across the ultraviolet and visible regions. The key material in focus is silver iodide/poly-2-aminothiophenol-intercalated iodide (AgI/P2ATP-I), prepared through two sequential reactions involving the oxidation of 2-aminothiophenol followed by a reaction with silver salt. The resulting material comprises semispherical particles of 80 nm diameter and exhibits a bandgap of 1.96 eV. The efficiency of the H₂ gas generation process is assessed using the current density (J_ph) as a metric, with higher values indicating increased H₂ production rates. Under illumination, J_ph reaches a significant value of −0.038 mA cm⁻², showing promise relative to the negligible dark current (J_o). Moreover, J_ph values exhibit an upward trend, from −0.014 mA cm⁻² to −0.029 mA cm⁻², corresponding to escalating photon energies from 1.7 eV to 3.6 eV, respectively. The estimated H₂ production rate of 3.5 µmol/h cm² positions the AgI-P2ATP-I photocathode as a promising candidate for generating renewable energy from contaminated wastewater. Its advantageous attributes include ease of fabrication, cost-effectiveness, and scalability for mass production, rendering it attractive for industrial applications.