Controlling Metastability through Annealing of High-Entropy Nanoalloy Electrocatalysts to Boost Performance towards the Oxygen Evolution Reaction

TL;DR

This study demonstrates that controlled annealing of metastable high-entropy nanoalloy electrocatalysts significantly enhances their oxygen evolution reaction performance by inducing beneficial phase transformations and surface modifications.

Contribution

It introduces a novel approach of exploiting metastability in high-entropy nanoalloys via post-synthesis annealing to boost electrocatalytic activity.

Findings

Annealing induces crystallization and element partitioning in nanoalloys.

Heterostructured nanoparticles with reinforced carbon shells show 5-7 times higher activity.

Metastability exploitation improves electrochemical performance.

Abstract

Low-cost transition metal high-entropy nanoalloys are emerging as sustainable alternatives to platinum group electrocatalysts. Synthesis conditions of single-phase solid solutions can alter phase stability, causing surface composition changes that affect electrocatalytic performance. Here, we propose to exploit the metastability of carbon-doped Cantor alloy-based amorphous high-entropy alloy nanoparticles produced by nanosecond-pulsed laser synthesis in organic solvents. In situ electron microscopy reveals crystallization and partitioning of elements upon heating to 600 {\deg}C, forming heterostructured nanoparticles with reinforced carbon shells that exhibit a 5- to 7-fold enhancement of the electrocatalytic activity compared to the as-synthesized counterparts for the oxygen evolution reaction. We demonstrate the strategic utilization of phase metastability in high-entropy nanoalloys through post-synthesis annealing to enhance the electrochemical activity of laser-generated nanoparticles.