Bifunctional Fe active sites on carbon nitride and titanium-based 2D nanomaterials for efficient visible light-driven ciprofloxacin degradation and overall water splitting

Summary The soft magnetic FeS2/Fe2O3 (FeS/FeO)-incorporated 2D C3N4 and TiO2-x nanomaterials were successfully synthesized and characterized by various physicochemical techniques, including XRD, FTIR, XPS, HRTEM, UV–Vis, VSM-magnetism and PL. The photocatalytic performance of the materials was applied to activate potassium persulfate (PPS) and H2O2 for the antibiotic ciprofloxacin (CIP) degradation as well as for water splitting using the photoelectrochemical path. The results illustrated that the degradation efficiency of the best photocatalyst, FeS/FeO@10 %2DTiO2-x, was 90 % in the presence of PPS and 100 % in the case of H2O2, with rate constants equal to 12.1 × 10−3 min−1 and 17.6 × 10−3, respectively, at an optimized reaction condition of 100 ml of 20 ppm CIP, H2O2 = 1.7 × 10−4 M, PPS = 1 × 10−3 M, catalyst = 0.1 g, pH = 3.5, t = 180 min, and at r.t. The exceptional activity of FeS/FeO@10 %2DTiO2-x compared to other nanocomposites may be attributed to the efficient exciton separation via the Z-scheme transferring pathway and the continuous Fe2+ and Fe3+ shuttles that support the photoFenton activity. Numerous examinations, including those on toxicity, zero-point charge, total organic carbon, temperature and the suggested mechanism, are well evaluated and discussed. The FeS/FeO@4%TiO2black-C3N4 photoelectrocatalyst exhibited excellent HER capacities in neutral medium, with overpotentials of −0.546 V at 10 mA cm−2 whereas for OER it shows overpotentials of 1.09 V mV at 10 mA cm−2. It showed 1.65 V of cell voltage at 10 mA cm−2, while maintaining 80 % stability. Interestingly, the latter electrode’s high efficiency can be attributed to a variety of factors, including variations in spectral light absorption, a longer lifespan for photogenerated electron-hole pairs, a better charge transfer efficiency, and the integration of Ti3+ and Ov generated from Ti-black with C3N4.