Controllable incoherent growth of a surface toward gold nanocrystals with regular multi-bumps

Abstract

Gold nanocrystals (NCs) with regular multi-bumps have been prepared through incoherent growth of the surface of seeded gold rhombic dodecahedra (RD) with the aid of Ag cations in a PVP/DMF system. After the Ag cations and HAuCl₄ were added together into the growth system to react for 45, 60, 75 and 90 minutes, three kinds of intermediate products with pyramid-type bumps and final products with block-type bumps can be obtained, respectively. The facet variation from {110}-type, via {980}-type to {210}-type and finally to {100}-type in the bumped structure has been clearly defined to understand the morphology evolution and the corresponding process of incoherent growth. Different addition sequences of Ag cations and HAuCl₄ have been carried out to explore the interaction between the additives and the surface. It is speculated that the absorption of AgCl on the surface of Au RD NCs inhibits the deposition of gold atoms, which may induce the incoherent growth of the surface of Au NCs. To further validate the inhibition effect of AgCl on the surface, highly concentrated NaCl solution was added into the growth solution to dissolve AgCl and only normal cubes without any bumps can be obtained.