Electrosynthesis of high-entropy metallic glass nanoparticles for designer, multi-functional electrocatalysis

Matthew W Glasscott,Andy T Hoang,Sondrica Goines,Anthony R Bishop,Jeffrey E Dick,Andrew D Pendergast,Christophe Renault

doi:10.1038/s41467-019-10303-z

Abstract

Creative approaches to the design of catalytic nanomaterials are necessary in achieving environmentally sustainable energy sources. Integrating dissimilar metals into a single nanoparticle (NP) offers a unique avenue for customizing catalytic activity and maximizing surface area. Alloys containing five or more equimolar components with a disordered, amorphous microstructure, referred to as High-Entropy Metallic Glasses (HEMGs), provide tunable catalytic performance based on the individual properties of incorporated metals. Here, we present a generalized strategy to electrosynthesize HEMG-NPs with up to eight equimolar components by confining multiple metal salt precursors to water nanodroplets emulsified in dichloroethane. Upon collision with an electrode, alloy NPs are electrodeposited into a disordered microstructure, where dissimilar metal atoms are proximally arranged. We also demonstrate precise control over metal stoichiometry by tuning the concentration of metal salt dissolved in the nanodroplet. The application of HEMG-NPs to energy conversion is highlighted with electrocatalytic water splitting on CoFeLaNiPt HEMG-NPs.

Highlights

(HEMGs), may offer access to properties arising from dissimilar metal interactions, though these complex materials remain largely unexplored[16,17]
For cathodic alloy electrodeposition experiments, variability in NP coverage, size, and stoichiometric composition stems from three main issues: preferential precursor nucleation and growth on energetically favorable sites leading to uneven surface coverage, diffusion layer overlap between neighboring
We demonstrate the versatility of the electro-shock method and its application to designer, multifunctional electrocatalysis by synthesizing a novel CoFeLaNiPt High-Entropy Metallic Glasses (HEMGs)-NP electrocatalyst for cathodic and anodic water splitting

Summary

Introduction

(HEMGs), may offer access to properties arising from dissimilar metal interactions, though these complex materials remain largely unexplored[16,17]. We recently demonstrated a solution to the issues outlined above by confining metal salt precursors to water nanodroplets suspended in dichloroethane (DCE), allowing for the isolated delivery of a specific number of precursor salt molecules to a localized nucleation and growth domain upon nanodroplet collision with a conductor[24,25] In this method, termed nanodropletmediated electrodeposition, delivery of the precursor atoms to the substrate results from the formation of a ~10 nm droplet/electrode contact radius upon nanodroplet collision, which we recently exploited to observe the nucleation and growth of single Pt NPs in real time on ultramicroelectrodes (UMEs)[26]. A 55-ms carbothermal-shock followed by rapid quenching (105 K/s) played an integral role in the first reported fabrication of HEA-NPs by Hu et al in 201820

Methods

Results

Conclusion