ZnO nanocrystals with a high percentage of exposed reactive facets for enhanced gas sensing performance

Zinc oxide single crystals with a high percentage of exposed { 4   2 ¯   2 ¯   3 ¯ } reactive facet were prepared by a facile hydrothermal route. X-ray diffraction, field emission scanning electron microscopy, and high resolution transmission microscopy confirmed the faceted single crystal structure. Through the density functional theory (DFT) calculations, it is validated that the { 4   2 ¯   2 ¯   3 ¯ } surface of ZnO crystals has high surface energy. When used as a sensing material in gas sensors, ZnO crystals with dominating exposed { 4   2 ¯   2 ¯   3 ¯ } planes exhibited a superior sensitivity toward toxic and flammable gases.