One-dimension noble nanomaterials have promising applications in many fields, and their growth pattern control is significant to property modulation. Herein, we report a facile strategy with which the growth pattern of Ag on the Au nanorod (NR) or decahedral nanoparticle (NP) surface can be precisely controlled and various structured Ag/Au NRs can be synthesized. Achievement of growth pattern control is mainly attributed to the adjustable reaction kinetics of Ag– to Ag0. Slow and moderate reaction rate favor asymmetrical growth, producing Au-tipped Ag NRs and asymmetrical Ag–Au–Ag NRs, respectively. In the case of a fast reaction rate, symmetrical growth dominates and symmetrical Ag–Au–Ag NRs form. Furthermore, the prepared bimetallic NRs can be used as starting materials to generate other novel nanostructures (nanocups, nanonails, and longer Au-tipped Ag NRs). The result presented here is vital to both exploration of growth theory and constructing nanostructures of not only the Au/Ag bimetallic system but also possibly other noble bimetallic systems. Moreover, these prepared nanostructures could provide model materials for studying the physical properties (such as structure-dependent surface plasmon) or have potential applications in the medical field. For example, hollow nanocups can serve as containers for controlled release of drug, etc.

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Chemical doping with foreign atoms is an effective approach to significantly enhance the electrochemical performance of the carbon materials. Herein, sulfur-doped three-dimensional (3D) porous reduced graphene oxide (RGO) hollow nanosphere frameworks (S-PGHS) are fabricated by directly annealing graphene oxide (GO)-encapsulated amino-modified SiO2 nanoparticles with dibenzyl disulfide (DBDS), followed by hydrofluoric acid etching. The XPS and Raman spectra confirmed that sulfur atoms were successfully introduced into the PGHS framework via covalent bonds. The as-prepared S-PGHS has been demonstrated to be an efficient metal-free electrocatalyst for oxygen reduction reaction (ORR) with the activity comparable to that of commercial Pt/C (40%) and much better methanol tolerance and durability, and to be a supercapacitor electrode material with a high specific capacitance of 343 F g(-1), good rate capability and excellent cycling stability in aqueous electrolytes. The impressive performance for ORR and supercapacitors is believed to be due to the synergistic effect caused by sulfur-doping enhancing the electrochemical activity and 3D porous hollow nanosphere framework structures facilitating ion diffusion and electronic transfer.