Enhanced photocatalytic hydrogen generation and degradation performance using a novel design of dual Co and W single metal atom oxides on the interstitial atomic line of TiO2–g-C3N4–rGO

In this study, a TiO₂–g-C₃N₄–ethylene diamine-reduced graphene oxide photocatalyst incorporating dissolved heteropolyacid-cobalt (HPA-Co) was successfully synthesized using the hydrothermal method. The surface-dispersed CoW single atom molecules were generated as co-catalysts utilizing the HPA-Co in the presence of ethylene diamine and ethylene glycol. Notably, the use of HPA-Co as a molecular precursor enables the controlled formation of well-dispersed single CoW atoms on the hybrid, offering a unique approach not commonly reported in previous studies. The developed atomic-level engineering photocatalyst achieved a high H₂ generation rate of 27.40 mmol g⁻¹ h⁻¹ and a sulfathiazole (STZ) degradation efficiency of 99.7 %. Furthermore, it demonstrated excellent stability and reusability over five successive cycles of H₂ production and STZ photodegradation. The synthesized hybrid catalyst exhibits high photocatalytic effectiveness, enabling the purification of strongly contaminated (30 L of 50 mg/L Rhodamine B) saltwater using a specially designed wastewater treatment apparatus within about 5 h of direct sunlight radiation. Mass spectrometry was employed to identify photodegradation intermediates. The composite exhibits enhanced photocatalytic performance, attributed to synergistic effects among the components, improved charge separation, and extended light absorption. This atomic-level engineering introduces abundant active sites and facilitates interfacial charge transfer, resulting in a significantly higher hydrogen evolution rate. A potential Z-scheme approach was suggested for photocatalytic hydrogen generation efficiency. These findings contribute to the development of cost-effective, durable photocatalysts with rapid reaction kinetics and high H₂ generation and photodegradation efficiency.