Fabrication of hollow type-II and Z-scheme In2O3/TiO2/Cu2O photocatalyst based on In-MIL-68 for efficient catalytic degradation of tetracycline

In this work, a ternary In2O3/TiO2/Cu2O photocatalyst was prepared using simple annealing of In-MIL-68/TBOT, followed by electrodeposition of Cu2O. The prepared photocatalyst had a hollow structure and its components were in intimate contacts, which endow it with numerous catalytic active sites while facilitating the migration and separation of charge carriers. The In2O3/TiO2/Cu2O-600 had the highest photon fluence rate in degradation of tetracycline under visible light irradiation. Its apparent rate constant (k) was 0.0293 min−1, 7.2 and 3.8 times higher than that of In2O3 and In2O3/TiO2, respectively. The photoelectrochemical measurements and radical (h+ and ∙O2–) trapping experiments revealed that the prepared photocatalyst had the n-n type-II hybrid Z-scheme electron transfer pathways, which was the mechanism responsible for its high photocatalytic activity. This study provides a new insight into synthesis of type-II hybrid Z-scheme ternary heterostructures which may have potential applications in environmental remediation.