Pinecone-shaped ZnO nanostructures: Growth, optical and gas sensor properties.

Pinecone-shaped ZnO nanostructures have been fabricated on Si substrate by pulsed laser deposition. The scanning electron microscope images showed that pinecone-shaped ZnO nanostructure was 6-fold symmetry and has the rough surface on one end. X-ray diffraction, Raman spectra and X-ray photoelectron spectroscopy indicated that the ZnO nanostructures have high crystal quality and a large amount of surface states. Compared with ZnO nanowires and nanobelts, the oxygen gas sensor based on pinecone-shaped ZnO nanostructures has excellent selectivity, fast response and recover, and lower operating temperature. Meanwhile, the response properties are very stable over several circles.