pH Regulated Synthesis of Monodisperse Penta-Twinned Gold Nanoparticles with High Yield

Making different types of nanoparticles (NPs) in the same system is important not only for simplifying the synthesis but for reaching a universal growth mechanism and improving reproducibility. Here we show that different types of penta-twinned NPs (spheroid, bipyramid, and decahedron) with adjustable sizes can be prepared in one system with high purity by simply varying the initial pH of the growth solution. The generality of this method has been demonstrated with a variety of enols as a reductant, including ascorbic acid. The effect of pH was mainly attributed to the regulation of the reduction potential of reductants (RPRs), which determines the atomic deposition preference on the penta-twinned seed surface due to the lattice strain energy at the twin boundary and then the way it grows into final products. This method of controlling the atomic deposition by regulating the RPRs could be useful for the synthesis of other nanoparticles through the seed-mediated method.