From multi- to single-hollow trimetallic nanocrystals by ultrafast heating

Abstract

Metal nanocrystals (NCs) display unique physicochemical features that are highly dependent on the nanoparticle dimensions, anisotropy, structure, and composition. The development of synthesis methodologies that allow us to tune such parameters finely emerges crucial for the application of metal NCs in catalysis, optical materials, or biomedicine. Here, we describe a synthetic methodology to fabricate hollow multimetallic heterostructures using a combination of seed-mediated growth routes and femtosecond pulsed laser irradiation. The envisaged methodology relies on the co-reduction of Ag and Pd ions on gold nanorods (Au NRs) to form Au@PdAg core–shell nanostructures containing small cavities at the Au-PdAg interface. The excitation of Au@PdAg NRs with low fluence femtosecond pulses was employed to induce the coalescence and growth of large cavities, forming multihollow anisotropic Au@PdAg nanostructures. Moreover, single-hollow alloy AuPdAg could be achieved in high yield by increasing the irradiation energy. Advanced electron microscopy techniques, energy-dispersive X-ray spectroscopy (EDX) tomography, X-ray absorption near edge structure (XANES) and FDTD (finite differences in the time domain) simulationsallowed us to characterize the morphology, structure, and elemental distribution of the irradiated NCs in detail. The ability of the reported synthesis route to fabricate multimetallic NCs with unprecedented hollow nanostructures brings attractive prospects for the fabrication of tailored high-entropy alloy nanoparticles.