Establishing photocatalysis-self-Fenton system over a S-scheme Fe/Fe₂O₃@CuBi₂O₄ for enhancing TC removal via in-situ generating H₂O₂ and Fe/Cu dual-metal electron cycle: Radical and non-radical pathways

A S-scheme Fe/Fe₂O₃@CBO photocatalyst was synthesized via a grinding calcination method, proficiently degrading tetracycline via radicals and non-radical. The reaction rate of Fe/Fe₂O₃@CBO-20 was recovered to 0.0255 min⁻¹ that is 4.3 and 7.3 times as many as pristine Fe/Fe₂O₃ and CBO after introducing visible light at the degradation process. The characterization outcomes also bear out that the S-scheme heterojunction is formed by passivation layer Fe₂O₃ and CBO, which enhances the visible light responsiveness of catalyst and promotes the separation and transfer of photogenerated electrons to generate h⁺ and [rad]O₂⁻. Meanwhile, the molecular oxygen is more easily activated to form H₂O₂ due to the strong reduction potential of the CB (−1.21 eV), further to facilitate the transformation of [rad]O₂⁻ to ¹O₂. And the carriers excited in CBO activate Cu⁺, forming a Cu/Fe dual-metal electron cycle. The generated Fe²⁺ reacts with H₂O₂ to establish photocatalysis-self-Fenton system to generate ·OH. Additionally, the high TC removal in simulated aquatic environment exhibit that the catalytic performance is slightly affected by practical wastewater and the cyclic experiment show the stability and practicality. In conclusion, innovatively employing Fe/Fe₂O₃ for pollutant degradation via photocatalytic technology, this research paves a promising and efficacious pathway for the application of Fe/Fe₂O₃.