Bimetallic alloy nanoparticles from molecular approaches : synthesis, characterization and their magnetic and electrocatalytic applications

Abstract

Bimetallic alloy nanoparticle (NP) is an important class of nanomaterials, exhibiting unique and superior properties in magnetic and electrocatalytic applications compared to monometallic NP. The synthesis of bimetallic alloy NPs by molecular approaches has aroused much interest since it can construct nanostructures at the molecular level before NP formation. To start with, a brief introduction on bimetallic alloy NPs including their magnetic and electrocatalytic properties, common synthetic methods and applications was presented in Chapter 1. In Chapter 2, a series of FePd bimetallic complexes were designed to explore the self-assembling property, which was further planned to construct FePd bimetallic nanoparticles. A seed-growth supramolecular polymerization of the FePd complex was realized to form nanoribbons with controllable size. The complex with an ordered pattern was fulfilled by nanoimprint lithography, and the magnetic FePd nanoparticles were obtained from the pyrolysis approach. NiCu bimetallic alloy NP is a kind of ferromagnetic nanoparticles in which the Curie temperature can be tuned to around 293 K (room temperature) by changing its metal composition. In Chapter 3, in order to synthesize NiCu NPs with controllable size and composition, several synthetic methods were applied, and their pros and cons were demonstrated. Microemulsion method was finally applied to synthesize Ni0.72Cu0.28 alloy NPs with tuneable particle size up to 300 nm in diameter. This material has a potential application as a recyclable electrocatalysts in hydrogen evolution reaction (HER). In Chapter 4, in order to synthesize Pt-alloyed bimetallic NPs for electrocatalytic HER, some two-dimensional metal organic frameworks (2D MOFs) were synthesized. Metal-coordinated tetrapyridyl porphyrins and Pt were adopted as the monomer and the linker, and the corresponding MPt alloy NPs were obtained from pyrolysis. The HER performance of NPs showed excellent results over a universal pH range, which was due to the unique properties of metal alloy NPs. In Chapter 5, the nanocomposites of single-wall carbon nanotubes (SWCNTs) embedded with MPt alloy NPs were synthesized. By pyrolysis of the MOF-coated SWCNTs, it was shown that the introduction of SWCNTs optimized the performance of electrocatalytic HER.