S. Sakurai, J. Cho
Binghamton University - State University of New York,
Keywords: ZnO, nanoplates, 2-dimensional, photocatalytic, templated growth, hydrothermal
Summary:Two-dimensional (2-D) nanomaterials have recently received considerable attentions with their unique characteristics, which were not seen in their bulk and 1D counterparts. Zinc oxide (ZnO) is one of the most promising functional materials as it is chemically stable, non-toxic and available at low cost. To synthesize the 2-D ZnO platelets, ZnO has to grow in the a-axis while suppressing its growth in the c-axis. To control the growth direction, we prepared a seed layer of r-plane (1-102)-oriented aluminum oxide (Al2O3) spin coated on Si (111) substrate. On this alumina template, ZnO nanoplates were hydrothermally grown in the a-axis direction under various process conditions. As a lattice mismatch between a-plane (11-20) of ZnO and r-plane of Al2O3 is only 1.53%, ZnO grows epitaxially along the a-axis. Such nanoplates contained very high concentration of the surface defects and were off-stoichiometric, thereby making them into very effective photocatalytic surfaces for degradation of organic contaminants. In addition, these vertically-stacked ZnO nanoplate surfaces showed the electrical properties that strongly depend on the presence of oxygen and temperature. As a result, the templated growth of the 2-D ZnO nanoplates shows the great potential to create a functional surface that can be very sensitive to external stimuli such as light and environment by adjusting the defect concentration and type. This presentation will highlight current research progresses made for the control of these defects to tailor the photocatalytic properties of the nanoplate-stacked surfaces.