Type-II ZnO nanorod–SnO2 nanoparticle heterostructures: characterization of structural, optical and photocatalytic properties

Abstract

In this work we report, for the first time, on the preparation of ZnO nanorod–SnO₂ nanoparticle (ZnO NR–SnO₂ NP) heterostructures by a simple two-step thermal evaporation approach. Systematical characterization of the product reveals that the rutile SnO₂ NPs, with a diameter of about 20 nm, are uniformly and tightly decorated on the entire ZnO NRs. Photoluminescence (PL) investigation on the ZnO NR–SnO₂ NP heterostructures shows that they exhibit a significantly decreased UV emission compared with the bare ZnO NRs, revealing an efficient charge separation arising from the type-II band alignment. Enlightened by this merit, photocatalytic behavior of the synthesized heterostructures is studied, which shows a remarkably enhanced photodegradation performance of rhodamine B (RhB) in contrast to the pure ZnO NRs. We also carry out the stability test of the ZnO NR–SnO₂ NP heterostructures and the result indicates an extremely high adhesion nature between the ZnO NR and the coated SnO₂ NPs. This advantage endowed with the thermal evaporation approach can lead to an efficient spatial charge separation between the ZnO NR and the SnO₂ NPs and thus effectively minimize the charge recombination along three-dimensional heterointerfaces, which makes such ZnO NR–SnO₂ NP architectures highly promising for a wide range of photovoltaic and photocatalytic applications.