Novel Single-Crystalline Hierarchical Structured ZnO Nanorods Fabricated via a Wet-Chemical Route: Combined High Gas Sensing Performance with Enhanced Optical Properties

Hierarchical structured ZnO nanorods have been fabricated via a wet-chemical approach for the development of multifunctional ZnO materials possessing excellent optical and gas sensing properties simultaneously, which was a great challenge because of their opposite requirements on morphology and structure. On the surface of the as-fabricated ZnO nanorods, thornlike single-crystalline nanostructures are developed in a large density. The development of crystal defects and the minimization of surface energy are suggested as the growth mechanism. On the basis of UV-vis absorption, room-temperature photoluminescence spectra, and gas sensing measurement, the as-prepared products exhibit combined highly sensitive gas sensing performance with excellent optical properties because of their hierarchical morphology and single-crystal line structure, confirming the feasibility for the design of multifunctional ZnO by constructing hierarchical structure. Besides the traditional doping routes, the fabrication of hierarchical structure can be potentially extended for the design of other multifunctional semiconductor materials.