Sustainable and stable hydrogen production over petal-shaped CdS/FeS2 S-scheme heterojunction by photocatalytic water splitting

One-dimensional CdS nanorods have garnered interest because of their highly visible light response, narrow bandgap, and negative potential at the conduction band edge, which are suitable for proton reduction. However, their poor charge separation and surface photocorrosion remain unresolved. In this study, CdS was synthesized with a 3D dendrite-like morphology to reduce its surface instability and junctioned with inexpensive FeS2 particles to extend the absorption region toward visible light and improve its photoactivity. The photocurrent density was increased 8.3 times, and the photoluminescence reduced by half in petal-shaped CdS/15% FeS2 compared with pure CdS. The petal-shaped CdS/15% FeS2 heterojunction catalyst exhibited significantly enhanced photostability and photocatalytic activity; when 10% lactic acid was used as a hole scavenger, the hydrogen generation rate was 22.91 mL g−1 for 10 h in pure CdS particles and 107.56 mL g−1 in the petal-shaped CdS/15% FeS2 particles. Moreover, the amount of hydrogen generated was maintained until 8th recycling experiments. The Cd and S ions eluted via photocorrosion were not detected after the reaction was complete. This was attributed to the petal-shaped CdS/FeS2 heterojunction system which protected the unstable CdS surface owing to its controlled morphology. The FeS2 junction improved visible light absorption facilitating the separation of photogenerated charges.