Abstract

This study introduces a new strategy utilizing poly(o-phenylenediamine) (POPD) to overcome the limitations of traditional solid-state Z-scheme photocatalysts. POPD was first selected for its tunability, stability, and interfacial compatibility in constructing a novel S-scheme heterojunction between twice-calcined graphite carbon nitride (CN) and zinc aluminate (ZAO). Femtosecond transient absorption spectroscopy (fs-TAS) confirmed that this design optimizes the dynamics of photogenerated charge carriers. Theoretical calculations indicated that close interface coupling through high interfacial binding with CN (-5.21 eV) and ZAO (-17.80 eV). Simultaneously, POPD facilitates the expansion and hybridization of the electronic states of ZAO/POPD/CN (ZPN), thereby optimizing the distribution of excitation energy and enhancing exciton transitions. The optimal ZPN efficiently degrades tetracycline (TC) and completely inactivates Escherichia coli (E. coli) under simulated sunlight. Systematic characterization and theoretical calculations validated the charge transfer pathways within the S-scheme heterojunction. These findings offer new insights into advancing the application of organic polymer in heterojunctions.