Design of Hydrothermally Derived Fe2O3 Rods with Enhanced Dual Functionality Via Sputtering Decoration of a Thin ZnO Coverage Layer

The Fe2O3-ZnO composite rods were successfully synthesized by combining hydrothermal growth of Fe2O3 rods and sputtering deposition of a thin ZnO coverage layer. Two types of the Fe2O3 rods with round and rectangular cross-sectional morphologies grown via control of the urea content in hydrothermal growth processes were used as rod templates to fabricate the Fe2O3-ZnO composite rods. The Fe2O3-ZnO composite rods exhibited an improved photoelectric conversion efficiency in the Fe2O3 rods via a construction of a heterogeneous structure. The photocatalytic degradation performance of rhodamine B dyes with Fe2O3 rods was substantially increased via sputtering decoration of a thin ZnO coverage layer on the Fe2O3 rods. Moreover, the Fe2O3-ZnO composite rods exhibited superior acetone vapor-sensing responses than the pristine Fe2O3 rods herein. The extended optical absorption ability together with the enhanced photoinduced charge separation efficiency via construction of the Fe2O3-ZnO heterogeneous system explained the improved photoactivity of the composite rods. Furthermore, the formation of a heterojunction between the Fe2O3 and ZnO increased the interfacial potential barrier height and enhanced the sensor resistance variation size upon exposure to the acetone vapor. This accounted for the improved gas-sensing performance of the Fe2O3-ZnO composite rods. The experimental results herein provide a promising approach to design Fe2O3-based composite rods with desirable photocatalytic and gas-sensing functionalities.