Atomically resolved Au52Cu72(SR)55 nanoalloy reveals Marks decahedron truncation and Penrose tiling surface
Yongbo Song, Yingwei Li, Hao Li, Feng Ke, Xiang Ji, Chuanjun Zhou, Peng Li, Manzhou Zhu, Rongchao Jin
Abstract
Abstract Gold-copper alloys have rich forms. Here we report an atomically resolved [Au 52 Cu 72 ( p -MBT) 55 ] + Cl − nanoalloy ( p -MBT = SPh- p -CH 3 ). This nanoalloy exhibits unusual structural patterns. First, two Cu atoms are located in the inner 7-atom decahedral kernel (M 7 , M = Au/Cu). The M 7 kernel is then enclosed by a second shell of homogold (Au 47 ), giving rise to a two-shelled M 54 (i.e. Au 52 Cu 2 ) full decahedron. A comparison of the non-truncated M 54 decahedron with the truncated homogold Au 49 kernel in similar-sized gold nanoparticles provides for the first time an explanation for Marks decahedron truncation. Second, a Cu 70 (SR) 55 exterior cage resembling a 3D Penrose tiling protects the M 54 decahedral kernel. Compared to the discrete staple motifs in gold:thiolate nanoparticles, the Cu-thiolate surface of Au 52 Cu 72 forms an extended cage. The Cu-SR Penrose tiling retains the M 54 kernel’s high symmetry ( D 5h ). Third, interparticle interactions in the assembly are closely related to the symmetry of the particle, and a “quadruple-gear-like” interlocking pattern is observed.