PNNL

Abstract

Creation of complex nanostructured materials through oriented attachment (OA) requires the manipulation of interparticle forces, including electrostatic repulsion, which depends strongly on surface potentials and can be modified by the solution environment. Here we show that time-dependent anisotropies in surface potential driven by competitive ion adsorption can 30 alter facet-selectivity during OA. This phenomenon enabled the synthesis of branched cubic Pt mesocrystals in which primary Pt nanoparticles initially attach on {100} facets to create a cubic core, but transition to branch formation through OA on {111} facets due to competitive ion adsorption driven by surface energy minimization. In both stages, electrostatic torques resulting from the anisotropy in surface potential enforce particle alignment. The findings provide a 35 generalizable approach for synthesizing complex nanomaterials through OA.