High entropy alloy nanoparticle formation at low temperatures

Abstract

Entropy-driven formation of high entropy alloy (HEA) nanoparticles from metal precursors requires high temperatures and controlled cooling rates. However, several proposed HEA nanoparticle synthesis strategies avoid the high-temperature regime. In our work, we address the question of how single-phase HEA nanoparticles can form at low temperatures. Investigating a system of five noble metal single source precursors, we combine in situ X-ray powder diffraction with multi-edge X-ray absorption spectroscopy to demonstrate that the formation of single-phase nanoparticles is governed by stochastic principles and the inhibition of precursor mobility during the formation process. The proposed formation principle is supported by simulations of the nanoparticle formation in a randomized process, rationalizing the experimentally found differences between two-element and multi-element metal precursor mixtures.

Structure-driven tuning of catalytic properties of core–shell nanostructures

“…Several papers have been devoted to the realization of experimental techniques for the synthesis of such complex alloys consisting of 11-21 metals. [208][209][210][211] Prior to the application of these materials in catalysis, it is necessary to carry out the identification of the properties that are mainly responsible for the optimization of the catalytic properties for a given reaction. Recently, the hydrogen evolution reaction has been tested on such objects, 212,213 indicating great prospects for the use of highentropy alloy nanoparticles in this reaction.…”

Synthesis of High Entropy Alloy Nanoparticles by Pulsed Laser Ablation in Liquids: Influence of Target Preparation on Stoichiometry and Productivity

“…[31] In high-temperature synthesis methods, entropy contributes to stabilizing multi-metallic phases, enabling the preparation of single-phase materials. [32] Carbother-mal shock synthesis of HEA NPs using 8 elements (Pt, Pd, Ni, Co, Fe, Au, Cu, and Sn elements) resulted in the formation of singlephase homogeneously mixed solid solution NPs. [29] The synthesis process however requires electrically conductive support materials, which limits its possibilities for large-scale synthesis.…”