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

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.