One-pot, high-yield synthesis of one-dimensional ZnO nanorods with well-defined morphology as a highly selective photocatalyst

Abstract

One-dimensional (1D) semiconductor ZnO nanorods have been successfully prepared via a facile surfactant-free hydrothermal method. Their structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption, photoluminescence spectra (PL) and electron spin resonance spectra (ESR). It is found that ZnO nanorods with diameters around 20–30 nm and lengths up to several micrometers are well-distributed. ZnO nanorods have been used to photocatalyze the aerobic oxidation of alcohols to aldehydes under ambient conditions. The results show that ZnO nanorods exhibit a markedly enhanced photoactivity and selectivity compared to their precursor, commercial ZnO, which can be ascribed to the special 1D morphology of ZnO nanorods leading to its favorable, selective adsorptivity toward the reactant of alcohols instead of the product of aldehydes, and the efficient separation of photogenerated charge carriers. A possible reaction mechanism for the photocatalytic selective oxidation of alcohols over ZnO nanorods has also been proposed. Our present work not only provides a facile, high-yield and surfactant-free approach for the fabrication of ZnO nanorods, but also enriches the chemistry of morphology-dependent functional properties of ZnO materials in the application of heterogeneous photocatalytic selective oxidation, which therefore could open a new doorway to utilize 1D semiconductor materials such as nanorods, nanotubes and nanowires as photocatalysts in selective transformation under ambient conditions.