Rapid Synthesis of High‐Entropy Oxide Microparticles

Abstract

High‐entropy nanoparticles have received notable attention due to their tunable properties and broad material space. However, these nanoparticles are not suitable for certain applications (e.g., battery electrodes), where their microparticle (submicron to micron) counterparts are more preferred. Conventional methods used for synthesizing high‐entropy nanoparticles often involve various ultrafast shock processes. To increase the size thereby achieving high‐entropy microparticles, longer reaction time (e.g., heating duration) is usually used, which may also lead to undesired particle overgrowth or even densified microstructures. In this work, an approach based on Joule heating for synthesizing high‐entropy oxide (HEO) microparticles with uniform elemental distribution is reported. In particular, two key synthesis conditions are identified to achieve high‐quality HEO microparticles: 1) the precursors need to be loosely packed to avoid densification; 2) the heating time needs to be accurately controlled to tens of seconds instead of using milliseconds (thermal shock) that leads to nanoparticles or longer heating duration that forms bulk structures. The utility of the synthesized HEO microparticles for a range of applications, including high‐performance Li‐ion battery anode and water oxidation catalyst. This study opens up a new door toward synthesizing high‐entropy microparticles with high quality and broad material space.

High-Entropy Oxide Derived from Metal–Organic Framework as a Bifunctional Electrocatalyst for Efficient Urea Oxidation and Oxygen Evolution Reactions

“…et al also prepared (CoCrFeMnNi) 3 O 4 HEOs following a similar high temperature (1050 °C) synthesis method. 27 Recently, Dong et al 28 prepared (MnFeCoNiCuZn) 3 O 4−x HEOs using a rapid Joule heating strategy at 1227 °C, and the obtained HEOs demonstrated high oxygen vacancies and efficient catalytic activity for the O E R . R e c e n t l y , X i a n g e t a l .…”

“…et al also prepared (CoCrFeMnNi) 3 O 4 HEOs following a similar high temperature (1050 °C) synthesis method . Recently, Dong et al prepared (MnFeCoNiCuZn) 3 O 4– x HEOs using a rapid Joule heating strategy at 1227 °C, and the obtained HEOs demonstrated high oxygen vacancies and efficient catalytic activity for the OER. Recently, Xiang et al prepared (Al 0.2 CoCrFeMnNi) 0.58 O 4−δ HEOs at the optimum temperature of 650 °C, and additional Al 0.2 was doped in (CoCrFeMnNi)­O 4 to modulate the HEOs for a high concentration of oxygen vacancies.…”

CoFeNiMnZnB as a High-Entropy Metal Boride to Boost the Oxygen Evolution Reaction

“…It is well known that the Fe presence, even in small quantities, enhances the OER activity of Ni- and Co-based catalysts. − , The origin of this enhancement has been a long-standing topic of debate. Among others, Fe 3+ ions have been reported to increase the electrical conductivity of the catalysts, contribute to the adsorption of OER intermediates, suppress the metal oxidation step, facilitating the O 2 evolution, help Ni 3+ oxidation to highly active Ni 4+ , or oxidize themselves to Fe 4+ , which contributes to O–O coupling …”

“…HEMs combine five or more elements into a stable solid solution. Various HEM families have been developed, including oxides, 11,12 phosphides, 13,14 and sulfides. 15−17 Owing to the outstanding strength, hardness, fracture toughness, and corrosion resistance of these materials, most previous studies on HEMs have focused on optimizing their mechanical properties.…”

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

“…116 3D, three-dimensional; HEA, high entropy alloy. O), 48,[122][123][124][125] sulfides (e.g., (CrMnFeCoNi)S x ), 111,126 metal dichalcogenides (e.g., (MoWVNbTa)S 2 ), 127 phosphates (e.g., (CoFeNiMnMo)P i ), 112,128 metal-organic frameworks (e.g., (NiCdCoCuZn)-ZIF), 129,130 metal carbide (and MXenes) (e.g., TiVNbMoC 3 and TiVCr-MoC 3 ), 113,114,131 and 2D van der Waals materials, 132 were also realized (Figure 5G). With the increase of research on high-entropy materials and innovative synthesis methods, more types of high-entropy compounds with various compositions and attractive characteristics can be explored in the future.…”