A general strategy for nanohybrids synthesis via coupled competitive reactions controlled in a hybrid process.

Rongming Wang,Wantai Yang,Xiaomiao Shen,Xiaodi Zhong,Yujun Song,Junmei Wang,Shuai Li,Yuanjun Song

doi:10.1038/srep09189

Abstract

A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

Highlights

Rongming Wang1*, Wantai Yang2*, Yuanjun Song1, Xiaomiao Shen3, Junmei Wang1, Xiaodi Zhong3, Shuai Li3 & Yujun Song1
Recalling the STEM-HAADF image of one single particle and the energy dispersive X-ray spectrometries (EDX) analysis for these NPs ensemble (Fig. s3d-ii), these results clearly suggest the gradient structure in these NPs, including Al alloyed metallic Ag cores, the Ag/Ag1 doped Al2O3 interlayer with the Ag/Ag1 dopant decreasing from the core to the surface coating, and the AlAgO2 at the outmost surface, which can be further confirmed by X-ray diffraction (XRD) analysis (Fig. 5f)
Generally, we have successful lly expanded simple programmed microfluidic processes (SPMPs) to a hybrid microfluidic and batch-cooling process for the synthesis of gradient coreshell nanohybrids based on the core alloying and shell gradient-doping strategy realized by coupled competitive reducing-nucleation and precipitation reactions

Summary

Introduction

Rongming Wang1*, Wantai Yang2*, Yuanjun Song, Xiaomiao Shen, Junmei Wang, Xiaodi Zhong, Shuai Li3 & Yujun Song. A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. Growth of nanoparticles can be www.nature.com/scientificreports well-terminated at the defined stage by rapid cooling the reaction solution from the microchannel in the collecting receiver with steeply reduced temperature This hybrid process was used in the structure and composition controlled synthesis of nanohybrids by coupling competitive reactions, or sequenced reducing-nucleation and co-precipitation, which were realized by introducing a second metal salt with low electrochemical potential (i.e., AlCl3, ZnCl2) into the primary-metal-salt solution. By adjusting the bi-channel solvents and kinetic parameters (e.g., reactant concentrations, flow rates and reaction temperatures) at each stage, the primary components with alloyed cores and the second components with the primary metal gradient-doping ZnO or Al2O3 as surface coatings can be successively formed. Ultra-small magnetic-dielectrics (e.g., FeAl@Al(1-x)FexOy), magneticsemiconductors (e.g., CoZn@Zn(1-x)CoxOy), plasmon-dielectrics (e.g., AgAl@Al(1-x)AgxOy) and plasmon-semiconductors (e.g., AuZn@ Zn(1-x)AuxOy) NPs of unique magnetic and optical properties can be synthesized using N-methyl-2-pyrrolidone (NMP) and/or water as bichannel solvents at a wide range of flow rates

Methods

Results

Conclusion