Malaz Suliman, Muhammad Tahir
High Resolution Image Download MS PowerPoint Slide Hydrogen (H 2 ) is gaining recognition as a renewable energy carrier, and seawater splitting offers a sustainable way to produce it. However, the process is complex due to the unclear effects of salt ions on photocatalysts. Meanwhile, toxic hydrogen sulfide (H 2 S) poses health risks, emphasizing the need for effective utilization. This study investigates the performance of an indium-loaded TiO 2 photocatalyst (In/TiO 2 ) for seawater splitting using H 2 S as a sacrificial agent, aiming to enhance H 2 production while utilizing this hazardous gas. While indium loading enhanced light absorption and suppressed charge recombination, the presence of NaCl improved electron transfer and resulted in a more favorable reduction potential. Thus, H 2 yields of 3% In/TiO 2 in 3.5 wt % NaCl solution produced 427.21 μmol·g –1 compared to only 66.59 μmol·g –1 produced from pure water after 1 h of irradiation. Interestingly, replacing methanol with H 2 S resulted in further increase in H 2 yield, reaching 733.10 μmol·g –1 from 3.5 wt % NaCl solution after 1 h of irradiation. At 0.5 wt % NaCl, the photocatalytic system achieved its highest hydrogen yield, whereas at 5 wt % the yield dropped sharply, falling to only about 54% of the value recorded at 0.5 wt %. Results also showed that individual seawater salts including NaCl, MgCl 2, CaCl 2, Na 2 SO 4, and KCl, at concentrations similar to those in natural seawater each contributed to enhanced H 2 production, though to varying degrees. Among them, MgCl 2 exhibited the highest yield of 897.80 μmol·g –1 after 1 h of irradiation. The proposed mechanism revealed the dual role of seawater ions and H 2 S in enhancing H 2 evolution over In/TiO 2 . Bisulfide ions scavenge photogenerated holes, while dissolved salts improve conductivity and charge transfer. Together, these effects enable a cost-effective and sustainable route for hydrogen production.