Tailoring lattice strain in ultra-fine high-entropy alloys for active and stable methanol oxidation

Abstract

High-entropy alloys (HEAs) have been widely studied due to their unconventional compositions and unique physicochemical properties for various applications. Herein, for the first time, we propose a surface strain strategy to tune the electrocatalytic activity of HEAs for methanol oxidation reaction (MOR). High-resolution aberration-corrected scanning transmission electron microscopy (STEM) and elemental mapping demonstrate both uniform atomic dispersion and the formation of a face-centered cubic (FCC) crystalline structure in PtFeCoNiCu HEAs. The HEAs obtained by heat treatment at 700°C (HEA-700) exhibit 0.94% compressive strain compared with that obtained at 400°C (HEA-400). As expected, the specific activity and mass activity of HEA-700 is higher than that of HEA-400 and most of the state-of-the-art catalysts. The enhanced MOR activity can be attributed to a shorter Pt-Pt bond distance in HEA-700 resulting from compressive strain. The nonprecious metal atoms in the core could generate compressive strain and down shift d-band centers via electron transfer to surface Pt layer. This work presents a new perspective for the design of high-performance HEAs electrocatalysts.

High‐entropy alloy catalysts: From bulk to nano toward highly efficient carbon and nitrogen catalysis

“…28,63,150 These fuel cells generally involve different electrocatalytic reactions during operation: the anode reaction is the oxidation of various carbon-based fuels, such as formic acid oxidation reaction (FAOR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR), while the cathode reaction is typically an ORR. 28,63,65 Until recently, due to the wide application of HEA catalysts, many researchers have applied HEA catalysts in these fuel oxidation reactions.…”

“…(G) d‐Orbitals of surface Pt atoms in the systems of Pt(111), HEA‐400, and HEA‐700. Reproduced with permission: Copyright 2021, Springer Nature 65 . (H) Schematic illustration of the PGM‐HEA electrocatalysis.…”

“…To further improve the MOR catalytic performance, Wang et al 65 fabricated PtFeCoNiCu HEA nanoparticles at different temperatures (i.e., 400°C and 700°C), and tuned their electrocatalytic activities via a surface strain strategy (Figure 9D). Compared with HEA‐400, HEA‐700 shows higher specific activity and mass activity in an acidic solution.…”

Pt–Ni Alloy Nanoparticles via High-Temperature Shock as Efficient Electrocatalysts in the Oxygen Reduction Reaction

“…With the rapid depletion of fossil fuels and increasing demand for clean energy, research on fuel cells and other renewable energy technologies has seen strong growth in the past few years. − The recent advances in anion exchange membranes have provided new opportunities for alkaline fuel cells (FCs). − Actually, great efforts have been made to develop nonprecious metals considering their low costs as well as abundance. , However, because of the poor activity and stability of nonprecious metals, , it turns out to be more feasible to integrate them with precious ones. − …”

Fluorination-enabled interface of PtNi electrocatalysts for high-performance high-temperature proton exchange membrane fuel cells

“…The main challenges to improve the HT-PEMFC performance and durability are the development of highly durable electrocatalysts and supports that are suitable to run at elevated temperatures with long durability. Carbon sup-ports undergo corrosion leading to delamination of catalyst particles and collapse of the catalyst-layer, further speeding up the dissolution and Ostwald ripening of Pt-based nanoparticles, and resulting in performance degradation or failure of fuel cells [7][8][9][10][11].…”