Self-assembly of gridlike zinc oxide lamellae for chemical-sensing applications

Hexagonal gridlike ZnO lamellae (GZL) with uniform thickness are synthesized by the o-phthalic acid-assisted hydrothermal method. Here, a systematic study of the assembly behaviors of gridlike ZnO lamellae obtained by the synergistic effect of urea and o-phthalic acid is presented. The morphology evolution and formation mechanism of GZL are also discussed in detail. The as-synthesized samples were characterized by powder X-ray diffraction, scanning electron microscopy, and transmission electron microscopy and electron diffraction spectroscopy. The results show that 2D ZnO lamellae are composed of nanotablets, which are jointed to form grids. The length and width of ZnO lamellae are about 1000 and 500 nm, respectively, and the thickness is about 30 nm. GZL morphology evolves from hexagonal ZnO nanotablets to lamellae with grids. The gas-sensing properties indicate that sensors fabricated from different materials present very different responses to volatile organic compounds. A GZL-based sensor has good response to acetaldehyde, and the response and recovery times are 1 and 6 s, respectively, when it was exposed to 1 ppm of acetaldehyde gas. The possibility of tuning the gas-sensing properties by adjusting the morphology makes GZL a novel candidate for more effective detection of a toxic, volatile gas with low concentration.