Synergistic enhancement of photocatalytic molecular oxygen activation by nitrogen defect and interfacial photoelectron transfer over Z-scheme α-Fe2O3/g-C3N4 heterojunction

Photoinduced molecular oxygen activation offers a promising strategy for oxidative degradation of organic pollutants, but the critical step of oriented electron delivery from the active sites into the stable O2 molecules presents a considerable challenge. Herein, we report the construction of a direct Z-scheme heterojunction with abundant nitrogen defects (α-Fe2O3/g-C3N4) for powering molecular oxygen activation by steering a specific migration route. This specific interfacial photoelectron transfer pathway showcases the establishment of an effective sequential photoelectron transfer channels between α-Fe2O3 and g-C3N4. The nitrogen defects on the g-C3N4 surface can not only serve as the oxygen adsorption sites, but also can act as the terminal electron sink to donate photoexcited high-energy electrons to the adsorbed O2. Therefore, the optimized α-Fe2O3/g-C3N4 exhibits greatly enhanced catalytic performance for molecular oxygen activation, and the degradation rate constant of tetracycline is 4.7 and 12 times higher than g-C3N4 and α-Fe2O3, respectively.