| AVS 60th International Symposium and Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS+NS-WeM |
| Session: | Nanostructures: Reactivity & Catalysis |
| Presenter: | J. Zhao, North Carolina State University |
| Authors: | J. Zhao, North Carolina State University A. Bagal, North Carolina State University Q. Yang, North Carolina State University X. Zhang, North Carolina State University C.-H. Chang, North Carolina State University M.D. Losego, North Carolina State University G.N. Parsons, North Carolina State University |
| Correspondent: | Click to Email |
ZnO has been used as photocatalyst to degrade organic compounds, such as phenol, phenol derivatives, naphthalene, anthracene, and dye molecules. In order to overcome the limitation of ZnO nanoslurries, immobilized photocatalyst with high S/V ratio nanostructure is needed. Previously, ZnO-nanowire-decorated pore-array films, polymer fiber mats and ZnO nano-plates have been fabricated and reported with enhanced photocatalytic properties. However, diffusion of dye molecules into nanostructures was found to limit the photocatalytic performance. Since the structures of these photocatalysts were not made periodic or uniform in size, the effects of nanostructure dimension could not be investigated. Periodic 3D nanostructures with tunable sizes are therefore needed.
A series of ZnO hierarchical 3D nanostructures were fabricated for photocatalytic applications. Nano-pillars were patterned on photoresist (PFi88A7) using interference lithography, and were coated with a conformal ZnO seed layer (~40nm) using atomic layer deposition (ALD). ZnO nanowires were grown onto the nano-pillars via hydrothermal synthesis. With varied growth time, we decorated the ALD ZnO coated nano-pillars with ZnO nanowires of different lengths (60~150nm). Scanning electron microscopy confirmed the 3D hierarchical nanostructures. Photodegradation kinetics of methyl orange was measured to characterize the photocatalytic property of the ZnO nanostructures. Apparent first order rate constant (kapp) of dye degradation was improved by 35% with ALD ZnO coated nano-pillars, compared with ZnO flat film catalyst. By decorating the nano-pillars with ZnO nanowires of 120 nm length, kapp was further increased by 88% to 1.75 h-1. We compared the photocatalytic property of our nanostructures with varied sizes. We will show how the nanostructures controlled the diffusion rate of dye molecules and affected the overall photocatalytic performance.