The study on the construction of S-scheme g-C3N4/MIL-101 heterojunctions through interface and built-in electric field modulation and their photocatalytic degradation performance of tetracycline

Slow charge transfer and a weak built-in electric field (BIEF) at the heterojunction interface critically hinder the construction of efficient S-scheme heterojunctions. Secondary calcination and ultrasonic treatment of g-C 3 N 4 enhance interfacial contact with MIL-101, shortening carrier migration paths. P and Mn doping increases the Fermi-level difference between g-C 3 N 4(C,S) and MIL-101, strengthening the BIEF to drive directional carrier migration. This facilitates the recombination of carriers with low-redox-potential at the heterojunction interface while spatially separating carriers with high-redox-potential, successfully constructing an S-scheme P-Mn-MCN (C,S) heterojunction. The optimized system delivers remarkable photocatalytic performance, achieving 98 % tetracycline hydrochloride degradation under visible light within 60 min.