Direct Observation of Distinct Nucleation And Growth Processes in Electrochemically Deposited ZnO Nanostructures Using in Situ XANES

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.