The evolution of well-aligned amorphous carbon nanotubes and porous ZnO/C core–shellnanorod arrays for photosensor applications

Abstract

Well-aligned amorphous carbon nanotube (a-CNT) and porous ZnO/C core–shell nanorod(NR) arrays were fabricated for the first time by a proposed deposition–etching–evaporation(DEE) route. The arrays were prepared by deposition of carbon on the surface ofwell-aligned ZnO NR arrays by thermal decomposition of acetone followed by spontaneousetching and evaporation of core-ZnO. By utilizing the decomposition of acetone aswell as distinct degrees of interaction between intermediate products and ZnO,well-aligned nonporous ZnO/C core–shell NR, porous ZnO/C core–shell NR, and a-CNTarrays were separately prepared by varying the working temperature from 400 to700 °C. Scanning electron microscopy and high-resolution transmission electronmicroscopy show that the thickness of carbon shells increases from 3 to 10 nmwith the increase in working temperature. Raman spectra demonstrate slightsp2 bonds of carbon, indicating small graphite regions embedded in amorphous carbon nanoshells. TheE2 peaks of ZnO reduce with the increase in substrate temperature. Photoresponsemeasurements of ZnO/C NR arrays shows enhancement of both photoresponsivity andresponse velocity, and the interference of humidity with regard to photosensing is effectivelyreduced by the capping of carbon nanoshells. The work not only provides an effective routeto improve the photosensing of semiconductor nanomaterials for practical applications, butalso sheds light on preparing various hollow carbon and porous ZnO/C core–shellnanostructures with distinct morphologies by employing the routes presented inthe paper on diverse ZnO nanostructures for optoelectrochemical applications.