A supramolecular H12SubPcB-OPhCOPh/TiO2 Z-scheme hybrid assembled via dimeric concave-ligand π-interaction for visible photocatalytic oxidation of tetracycline

Abstract The development of stable, efficient molecular-inorganic photocatalysts for organic pollutants degradation in wastewater remains a major challenge. Herein, a novel axially substituted supramolecular nanocrystalline subphthalocyanine H12SubPcB–OPhCOPh (SubPc-4) was successfully synthesized. By self-assembling supramolecular SubPc-4 on TiO2 via dimeric concave-ligand π-interaction, an molecular-inorganic Z-scheme photocatalytic system (SubPc-4/TiO2) was prepared exhibiting high photoactivity and stability towards the degradation of tetracycline (TC), methyl orange (MO) and bromophenol blue (BB). The photocatalytic degradation efficiency of TC, MO and BB with SubPc-4/TiO2 was 96.2 %, 98.0 % and 100 % within 180 min, approximately 3.2, 19.7 and 6.6 times larger than pristine TiO2, respectively. The constructed SubPc-4/TiO2 hybrid kept 88.5 % of its original photocatalytic activity toward TC after five photocatalytic cycles with respect to the first cycle, while bare TiO2 only kept 23.2 %. We reveal that this high photoactivity and photostability arises from the formation of an effective charge separation Z-scheme. This work demonstrates the potential of the SubPc-4/TiO2 molecular-inorganic Z-scheme photocatalyst in wastewater treatment.