Synthesis and Characterization of ZnO/Graphene Nanostructures for Electronics and Photocatalysis

Abstract

Recent rapid development of electronics and electro-optical devices demands affordable and reliable materials with enhanced performance. Forming nanocomposites of already well-known materials is one possible route towards novel functional materials with desirable synergistic enhanced properties. Incompatible chemical properties, mismatched crystal structures and weak bonding interactions between the substances, however, often limit the number of possible nanocomposites. Moreover, using an inexpensive, facile, large-area and flexible fabrication technique is crucial to employ the new composites in industrially viable applications.This thesis focuses on the synthesis and characterization of different zinc oxide/graphene (ZnO/GR) nanocomposites, well suited for optoelectronics and photocatalysis applications. Two different approaches of i) substrate-free random synthesis, and ii) template-assisted selective area synthesis were studied in detail. In the first approach, ZnO nanoparticles/rods were grown on GR. The obtained nanocomposites were investigated for better GR dispersity, electrical conductivity and optical properties. Besides, by adding silver iodide to the nanocomposite, an enhanced plasmonic solar-driven photocatalyst was synthesized and analyzed. In the second approach, arrays of single, vertically aligned ZnO nanorods were synthesized using a colloidal lithography-patterned sol-gel ZnO seed layer. Our demonstrated nanofabrication technique with simple, substrate independent, and large wafer-scale area compatibility improved the alignment and surface density of ZnO nanorods over large selective growth areas. Eventually, we found a novel method to further enhance the vertical alignment of the ZnO nanorods by introducing a GR buffer layer between the Si substrate and the ZnO seed layer, together with the mentioned patterning technique.The synthesized nanocomposites were analyzed using a large variety of experimental techniques including electron microscopy, photoelectron spectroscopy, x-ray diffraction, photoluminescence and cathodoluminescence spectroscopy for in-depth studies of their morphology, chemical and optical properties. vi Our findings show that the designed ZnO/GR nanocomposites with vertically aligned ZnO nanorods of high crystalline quality, synthesized with the developed low-cost nanofabrication technique, can lead to novel devices offering higher performance at a significantly lower fabrication cost.

(Nano)materials for electrochemical sensing applications in different fields

“…Another important aspect of ZnO is the potential to be grown in various morphologies on a wide range of substrates using different cost-efficient growth techniques. ZnO's exceptional properties coupled with its facile synthesis make it an ideal candidate for sensing applications [58]. Table 1 summarizes some morphologies, synthesis methods and applications of ZnO.…”

Effect of Deposition Time on Material Properties of ZnO Nanorods Grown on GZO Seed Layer by CBD

“…As far as the CBD technique is concerned, controlling the size and morphology of the nanorods has proven to be challenging that is why most researchers use a two-step process which involves pretreatment of the substrates and chemical bath deposition process [14,15]. Study reports that the ZNRs grown on Si substrate through CBD method displayed poor results and difficulty in reproducibility [16]. It is, thus, commonly agreed that ZnO seeding, by spin coating or sputtering, is essential for easy and convenient growth of a well-aligned ZNRs perpendicular to the substrates [17,18].…”