<p>Hydrogen gas (H₂) production from sanitation water represents a groundbreaking approach to utilizing an unconventional yet sustainable electrolyte source for green hydrogen generation. In this study, an innovative photocathode is synthesized using a nanocomposite of bismuth molybdate, bismuth sulfide, and poly(2-aminobenzene-1-thiol) (Bi₂MoO₆–Bi₂S₃/P2ABT). The synthesis involved a two-step process: first, the preparation of Bi₂MoO₆, and then the oxidation of 2-aminobenzenethiol to form the complete composite. The resulting nanocomposite exhibits exceptional optical properties, including a broad absorption spectrum and an optimal optical bandgap of 1.8 eV that estimate a promising photocatalytic application, particularly in harnessing solar energy to drive hydrogen evolution reactions. The photocathode is applied inside a three-electrode cell under full-spectrum white light, at different specific wavelengths, and in complete darkness. Under white light illumination, the current density (J_ph), which correlates directly with hydrogen gas production, is −&#xa0;0.19 mA.cm⁻² that decreased slightly under monochromatic light conditions, registering −&#xa0;0.18 mA.cm⁻² at 340 nm and −&#xa0;0.16 mA.cm⁻² at 730 nm, demonstrating the photocathode's responsiveness to different wavelengths. In dark conditions, the J_ph dropped significantly, highlighting the photocatalytic nature of the hydrogen production process. The evaluated H₂ rate under white light is 5.0 µmol/h per 10 cm². Notably, the photocathode’s fabrication process is cost-effective and straightforward, making it aviable candidate for large-scale applications. Utilizing sanitation water offers a dual benefit through its applications as an electrolyte: sustainable energy production and wastewater valorization.</p>