Architecting epitaxial-lattice-mismatch-free (LMF) zinc oxide/bismuth oxyiodide nano-heterostructures for efficient photocatalysis

Abstract

Developing efficient photocatalysts has been proved to be of great importance for many emerging applications, including the removal of recalcitrant organic pollutants in wastewaters and transforming solar energy into important chemical feedstocks. One of the major challenges for high performance photocatalysts is that most semiconductor-mediated photocatalysts suffer severe charge recombination which finally hinders the overall photocatalytic efficiency. Herein, a delicately designed epitaxial grown heterostructure composed of zinc oxide (ZnO) nanowire and ultra-small bismuth oxyiodide (BiOI) nanoflakes was synthesized featuring quasi-free lattice mismatch at the ZnO/BiOI interface. With the advances of suitable p–n junction energy band alignment and minimized lattice mismatch, the synthesized ZnO/BiOI heterostructure shows significantly high interfacial charge transfer and separation efficiency. The high performance heterostructured photocatalyst was applied for the photodegradation of Bisphenol-A (BPA) in an artificial organic wastewater. The results showed that the epitaxial-LMF heterostructure is much superior to both ZnO nanowires and BiOI micro-sheets in catalytic efficiency. Analyzing the time-resolved kinetic features of photo-induced charge carriers revealed that it is the high-degree lattice match at the ZnO/BiOI interface that contributes to the significant charge-separation in the LMF heterostructure, leading to the substantial improvement of photocatalytic efficiency. An interesting finding is that a strong Foster-resonance energy transfer (FRET) from ZnO to BiOI in the heterostructure was observed, which could enhance the solar energy utilization. This study provides a general strategy to improve the interfacial charge separation efficiency of heterostructured photocatalysts, thereby greatly promoting the photocatalytic performance.