Regio-selective growth of plates on Au nanorods

Morphological control is extremely difficult during the second-stage growth on existing nanoparticles . Here, we show that it is possible to combine nanorod and nanoplate morphologies by using partially encapsulated polystyrene- block -poly(acrylic acid) shells as the mask. Au nanoplates were grown selectively from the exposed surface of the Au nanorod, with consistent orientation for each nanorod. As such, we achieve three levels of synthetic control simultaneously: 1) the polymer mask focuses the Au deposition onto a few sites, so that the nanoplates could extend out prominently; 2) the longitudinal extension of the nanorod could be shifted to the traverse growth of nanoplates by using iodide ions as the inhibitor; 3) the nanoplates grow from only one of the twin planes because of the dynamic competition via the depletion sphere mechanism.