  The electrochemical deposition of ZnO hierarchical nanostructures directly
from PHEMA hydrogel coated electrodes has been successfully demonstrated. A
variety of hierarchical ZnO nanostructures, including porous nanoflakes,
nanosheets and nanopillar arrays were fabricated directly from the PHEMA
hydrogel coated electrodes. Hybrid ZnO-hydrogel composite films were formed
with low zinc concentration and short electrodeposition time. A dual-layer
structure consisting of a ZnO/polymer and pure ZnO layer was obtained with zinc
concentration above 0.01 M. SEM observations and XPS depth profiling were used
to investigate ZnO nanostructure formation in the early electrodeposition
process. A growth mechanism to understand the formation of ZnO/hydrogel hybrid
hierarchical nanostructures was developed. The I-V characteristics of the
ZnO-hydrogel composite films in dark and under ultraviolet (UV) illumination
demonstrate potential applications in UV photodetection.
