Web Release Date: February 6,
Direct Observation of Distinct Nucleation and Growth Processes in Electrochemically Deposited ZnO Nanostructures Using in Situ XANES
and
Industrial Research Limited, P.O. Box 31-310, Lower Hutt, New Zealand, Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, and Department of Materials and London Centre for Nanotechnology, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
Received: July 23, 2007
In Final Form: September 23, 2007
Abstract:
In situ synchrotron X-ray absorption was used to study the nucleation and growth of ZnO nanostructures electrochemically deposited from aqueous solutions. A fixed-energy approach was used, which facilitates faster time resolution for systems that are not amenable to transmission measurements and where species-specific information has so far been elusive. Films formed at low potentials (-0.97 V vs Ag/AgCl) show instantaneous nucleation, continued growth, and coalescence of the nanorods. The resultant film is dense with narrow dispersion of rod diameters. At less negative deposition potentials (-0.77 V vs Ag/AgCl), the nucleation is more protracted, resulting in a polydispersed film. In this higher potential region, the growth rates are slower, and there is less evidence of coalescence in the deposited structures, with continued growth along the c-axis only.
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