(418a) Controllable Synthesis of ZnO Nanocrystals

In this report, we present a one-pot chemical solution method based upon gradual heating of premixed precursors, in contrast to more common hot-injection methods, for controllable synthesis of ZnO nanocrystals. In general, this type of method is much more amenable to scale-up than hot-injection methods that can be very sensitive to mixing rates, which in turn are difficult to maintain at larger scales. By tuning the mixture of solvent and surfactant (surface capping) agents, we have prepared ZnO nanocrystals with diverse morphology, size and photoluminescence properties. These include needle-like, branched, conical, and porous nanostructures as well as quantum dots with controllable size from 2 to 10 nm.  Moreover, by systematically varying factors such concentration of monomer, identity of surfactants, temperature and reaction time, qualitative understanding of the nucleation and growth process has been developed. Ostwald ripening induced shape evolution is also observed and discussed.