Ultrafast Synthesis of High Entropy Oxide Nanoparticles by Flame Spray Pyrolysis

Phakatkar, Abhijit H.; Saray, Mahmoud Tamadoni; Rasul, Golam; Sorokina, Lioudmila V.; Ritter, Timothy G.; Shokuhfar, Tolou

doi:10.1021/acs.langmuir.1c01105

Cited by 71 publications

(48 citation statements)

References 66 publications

(124 reference statements)

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“…22 demonstrates an efficient catalytic performance with an overpotential of 325 mV to achieve a current density of 10 mA cm −2 and also shows excellent stability for 50 h. 23 Until now, various methods have been developed for preparing HEOs, particularly for those with Fe, Ni, Co, Cr, and Cu metals, and the potential applications of HEOs in different areas have also been explored. In recent years, reverse coprecipitation, 21 nebulized spray pyrolysis, solid phase sintering, 24 and flame spray pyrolysis 25 have been mainly adopted for HEOs synthesis. For instance, Talluri et al 26 employed a reverse coprecipitation approach followed by 750 °C heat treatment to fabricate (CrMnFeCoNi) 3 O 4 HEO.…”

Section: Introductionmentioning

confidence: 99%

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

Fereja

Zhang

Fang

et al. 2022

ACS Appl. Mater. Interfaces

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High-entropy oxides (HEOs) offer unique features through a combination of incompatible metal cations to a single crystalline lattice. Owing to their special characteristics such as abundant cation compositions, high entropy stabilization, chemical and thermal stability, and lattice distortion effect, they have drawn ever-increasing attention for various applications. However, very few studies have been reported for catalytic application, and developing HEOs with large surface areas for efficient catalytic application is still in infancy. Herein, we design nanostructured HEO of (FeNiCoCrCu) 3 O 4 using metal−organic frameworks (MOFs) as sacrificial templates to achieve a large surface area, high density of exposed active sites, and more oxygen vacancies. Single-crystalline phase HEOs with surface area as large as 206 m 2 g −1 are produced and further applied as bifunctional electrocatalysts for the urea oxidation reaction (UOR) and oxygen evolution reaction (OER). Benefiting from enhanced oxygen vacancies and a large surface area with abundant exposed active sites, the optimized HEO exhibited excellent electrocatalytic activity toward UOR with a very low potential of 1.35 V at the current density of 10 mA cm −2 and showed long-term stability for 36 h operation, making a significant catalytic performance over previously reported HEOs. Moreover, the HEO demonstrated an efficient catalytic performance toward OER with a low overpotential of 270 mV at 10 mA cm −2 and low Tafel slope of 49 mV dec −1 . The excellent catalytic activity is ascribed to the starting MOF precursor and favorable high-entropy effect.

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Section: Introductionmentioning

confidence: 99%

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

Fereja

Zhang

Fang

et al. 2022

ACS Appl. Mater. Interfaces

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“…Overall, no significant changes are observed in the high-resolution spectra of Mg, Zn, Cu, and Ni after doping (Figure S3, Supporting Information, and Figure 3a,b). ≈16% Cu 1+ is found in the fitted Cu 2p 3/2 spectrum, [31] which may give birth to oxygen vacancies in MO. Notably, the proportion of Co 3+ increased from 12.6% to 19.5% after the incorporation of Li (Figure 3c), [32] revealing that Co participates in charge compensation to a certain extent.…”

Section: Resultsmentioning

confidence: 99%

Kinetically Accelerated Lithium Storage in High‐Entropy (LiMgCoNiCuZn)O Enabled By Oxygen Vacancies

Liu

Xing

et al. 2022

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High‐entropy oxides (HEOs) are gradually becoming a new focus for lithium‐ion battery (LIB) anodes due to their vast element space/adjustable electrochemical properties and unique single‐phase retention ability. However, the sluggish kinetics upon long cycling limits their further generalization. Here, oxygen vacancies with targeted functionality are introduced into rock salt‐type (MgCoNiCuZn)O through a wet‐chemical molten salt strategy to accelerate the ion/electron transmission. Both experimental results and theoretical calculations reveal the potential improvement of lithium storage, charge transfer, and diffusion kinetics from HEO surface defects, which ultimately leads to enhanced electrochemical properties. The currently raised strategy offers a modular approach and enlightening insights for defect‐induced HEO‐based anodes.

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“…X-ray diffraction (XRD) revealed the good crystallinity of the senary HEO, which featured a typical spinel structure (i.e., (Mn,Fe,Co,Ni,Cu,Zn) 3 O 4−x ) that agreed with literature reports based on similar elemental compositions (Figure 2C, red; the diffraction pattern of CoFe 2 O 4 was selected from the PDF database as a reference). [19,26,27,29] In comparison, the senary oxide prepared by conventional furnace heating at 1100 K for 2 h in air showed relatively poor crystallinity as evidenced by the weak peak intensities (Figure S1, Supporting Information). Interestingly, when conducting the high-temperature rapid heating process with the same precursor mixture at lean O 2 conditions (i.e., 30 ppm O 2 in Ar), we observed impurity peaks compared to the standard spinel crystal structure (Figure 2C, black).…”

Section: Introductionmentioning

confidence: 99%

Rapid Synthesis of High‐Entropy Oxide Microparticles

Dong

Hong

Gao

et al. 2022

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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.

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Ultrafast Synthesis of High Entropy Oxide Nanoparticles by Flame Spray Pyrolysis

Cited by 71 publications

References 66 publications

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

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

Kinetically Accelerated Lithium Storage in High‐Entropy (LiMgCoNiCuZn)O Enabled By Oxygen Vacancies

Rapid Synthesis of High‐Entropy Oxide Microparticles

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