Water process/treatment by a S-scheme Fe2O3/TiO2 heterojunction photocatalyst for excellent antibiotic degradation/CO2 reduction/H2 production; process optimization and mechanistic insights

A facile synthesis approach was employed to fabricate a binary Fe₂O₃/TiO₂ nanocomposite (FeTi4-400) for enhanced photocatalytic hydrogen (H₂) production, cephalexin degradation and CO₂ reduction under visible light irradiation. Compared to pristine TiO₂, FeTi4-400 exhibited improved visible light absorption and promoted charge carrier separation, leading to increased H₂ production rate and CO₂ conversion into CH₄ and CO. This improvement can be attributed to the formation of an S-scheme heterojunction, along with the desirable properties of FeTi4-400, including visible light activity, high surface area, and strong CO₂ adsorption. The photocatalyst achieved a maximum H₂ production rate of 649 μmol/g·h⁻¹, exceeding that of pure TiO₂. Similarly, the highest CO production rate of 16.44 μmol/g·h⁻¹ was attained with FeTi4-400. Furthermore, FeTi4-400 achieved excellent cephalexin degradation (96 %) under optimal conditions, with a degradation rate constant of 0.01 min⁻¹. A plausible cephalexin degradation pathway over FeTi4-400 is proposed. Transient photocurrent measurements and EIS analysis corroborated a significant enhancement in photocatalytic activity for FeTi4-400, attributed to the efficient separation of photogenerated electron-hole pairs. Stability studies demonstrated consistent cephalexin degradation by FeTi4-400 over five consecutive cycles without noticeable photocatalyst deactivation. This work presents a novel strategy for fabricating low-cost, efficient, and readily synthesized nanomaterials for applications in solar energy conversion and environmental remediation.