Tunning heterostructures interface of Cu2O@HKUST-1 for enhanced photocatalytic degradation of tetracycline hydrochloride

Abstract

Cu2O is an attractive material for the architectural design of integrated nanomaterials in photocatalysis. Herein, a contrastive study was carried out to explore the influence of morphology/exposed Cu2O facets on the template growth process and the difference of fabricated composites in photocatalysis performance. A series of Cu2O@HKUST-1 with core–shell structure was developed via a self-confinement strategy, in which Cu2O nanocrystals with various shapes (cube, truncated octahedron and octahedron) act as self-confinement template to grow Cu-based metal–organic frameworks (HKUST-1) shell. It was revealed that the growth of HKUST-1 on Cu2O crystal depended on the original Cu2O crystal. The exposure of (111) facet in Cu2O was more favorable to the growth of HKUST-1 than (100) crystal plane. Optical and photoelectrochemical characterizations revealed that the cubic Cu2O@HKUST-1 exhibited the outstanding light response and most efficient interfacial charge transfer and separation among three types of composites. As a result, the degradation rates of tetracycline hydrochloride (TC-HCl) by cubic Cu2O@HKUST-1 under the visible light irradiation was 95.35% within 60 min, which was much higher than truncated octahedral Cu2O@HKUST-1 (78.81%) and octahedral Cu2O@HKUST-1 (66.58%). Mechanism explorations including radical capture experiments, electron paramagnetic resonance and band structure analysis showed that type II heterojunction was formed in cubic Cu2O@HKUST-1 and truncated octahedral Cu2O@HKUST-1, which was conducive to the separation and transfer of photo-generated carriers. However, type I heterojunction existed in octahedral Cu2O@HKUST-1 lead to the recombination of photocarriers. These findings revealed the interface-dependent photocatalytic performance in Cu2O@HKUST-1 and provided useful guidance for controllable construction of photocatalysts with heterojunction structure.