A novel solar photo-Fenton system with self-synthesizing H2O2: Enhanced photo-induced catalytic performances and mechanism insights

To solve problems of consecutive H2O2 external supplement and reutilization difficult of free Fe2+ ion in traditional homogeneous photo-Fenton, an efficient solar photo-Fenton system with self-supplying H2O2 was developed based on a heterogeneous catalyst of alpha-Fe2O3/g-C3N4. The microstructure, physicochemical and photoelectric properties of the optimal alpha-Fe2O3/g-C3N4 were characterized. It was found that the introduced alpha-Fe2O3 significantly enhanced the photoeletrochemical performances of g-C3N4. Rhodamine B and tetracycline hydrochloride were degraded in this solar photo-Fenton system with alpha-Fe2O3/g-C3N4, and the corresponding degradation rates reached to 96% (in 90 min) and 95% (in 150 min) at neutral pH circumstance respectively, which were much higher than that of single g-C3N4 and alpha-Fe2O3. The efficient degradation performance was attributed to the effective separation and rapid transfer of photo-generated charge carriers derived from classic Z-scheme type. Accordingly, it was deduced that H2O2 can produce on the g-C3N4 surface firstly under simulated solar irradiation, and the efficient removal of contaminant could be ascribed to oxidation by amount of center dot OH predominantly derived from H2O2 decomposition on the alpha-Fe2O3, which was verified by trapping experiments and EPA analysis. In addition, center dot O-2(-) and h(+) also played supporting roles. The main significance of this study gives a new insight into photo-Fenton.