Development of a novel high-entropy alloy with eminent efficiency of degrading azo dye solutions.

Z Y Lv,B Jia,Y Wu,Z P Lu,H Wang,X J Liu

doi:10.1038/srep34213

Abstract

In addition to its scientific importance, the degradation of azo dyes is of practical significance from the perspective of environmental protection. Although encouraging progress has been made on developing degradation approaches and materials, it is still challenging to fully resolve this long-standing problem. Herein, we report that high entropy alloys, which have been emerging as a new class of metallic materials in the last decade, have excellent performance in degradation of azo dyes. In particular, the newly developed AlCoCrTiZn high-entropy alloy synthesized by mechanical alloying exhibits a prominent efficiency in degradation of the azo dye (Direct Blue 6: DB6), as high as that of the best metallic glass reported so far. The newly developed AlCoCrTiZn HEA powder has low activation energy barrier, i.e., 30 kJ/mol, for the degrading reaction and thus make the occurrence of reaction easier as compared with other materials such as the glassy Fe-based powders. The excellent capability of our high-entropy alloys in degrading azo dye is attributed to their unique atomic structure with severe lattice distortion, chemical composition effect, residual stress and high specific surface area. Our findings have important implications in developing novel high-entropy alloys for functional applications as catalyst materials.

Highlights

High-entropy alloys (HEAs) are emerging as a new class of metallic materials
The multi-principal elements feature leads to high mixing entropy and facilitates the formation of simple solid solution phases such as face-centered cubic (FCC) and/or body-centered cubic (BCC)[24] and/or hexagonal closed-packed (HCP)[25] which has been reported recently
It is interesting to notice that the solid-solution phase in high-entropy alloys (HEAs) are firstly formed upon solidification, which are kept to the ambient temperature due to the sluggish diffusion kinetics of HEAs, in a way analogous to the amorphous phase formation via the rapid solidification route[33]

Summary

Introduction

High-entropy alloys (HEAs) are emerging as a new class of metallic materials. Due to different atomic sizes of constituents, the lattice of structured HEAs usually is severely distorted. These intrinsic features render HEAs unique properties[26], such as high hardness[27,28], high strength[29], extraordinary fracture toughness[30], and excellent corrosion resistance[31,32]. In a way like metallic glasses[34], HEAs are metastable thermodynamically compared to the ordinary crystalline alloys for the atoms residing on the high energy state as a result of the severe lattice distortion[33,35]. Our findings certainly will extend applications of HEAs as functional materials

Methods

Results

Conclusion