Highly Stable Single-Phase FeCoNiMnX (X = Cr, Mo, W) High-Entropy Alloy Catalysts with Submicrometer Size for Efficient Oxygen Evolution

Abstract

The activity and stability of oxygen evolution reaction (OER) catalysts are often trade-offs and are both sizedependent. Theoretical calculations have predicted that some noble-metal-free high-entropy alloys (HEAs) are promising OER catalysts. However, their catalytic properties have not been proven because of the lack of a facile method to synthesize small-sized homogeneous HEA particles. Here, submicrometer-sized singlephase FeCoNiMnW HEA particles were prepared by electrochemical metallization in 900 s (at 900 °C). FeCoNiMnW shows the best OER activity (η = 355 mV at 500 mA cm −2 ) and durability of the three HEAs because the large total density of states of FeCoNiMnW accelerates the electrons' transport speed for OER. More importantly, the single-phase FeCoNiMnW continuously operated for 50 days at 500 mA cm −2 with an almost unchanged overpotential. Overall, this work offers a rapid and simple method to prepare various effective and long-lasting single-phase HEA catalysts with controllable sizes and enhanced OER performances.

A review of noble metal-free high entropy alloys for water splitting applications

“…Li et al 167 prepared a series of FeCoNiMnX (X = Cr, Mo, W) nanoparticles via molten salt electrolysis of oxide mixtures coated onto nickel foam with particle sizes of approximately 5 mm, 2.5 mm and 400 nm for FeCoNiMnCr, FeCoNiMnMo and FeCoNiMnW, as shown in Fig. 15(a)-(c) respectively.…”