Preparation and electrical conductivity of (Zr, Hf, Pr, Y, La) O high entropy fluorite oxides

Zhang, Fengnian; Cheng, Fuhao; Cheng, Chufei; Guo, Meng; Liu, Yufeng; Miao, Yang; Gao, Feng; Wang, Xiaomin

doi:10.1016/j.jmst.2021.07.028

Cited by 31 publications

(7 citation statements)

References 53 publications

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“…Moreover, several classical proton conductors were also selected to compare and the data are summarized in Table S4 in the Supporting Information. From Table S4, the protonic conductivity of these compounds is independent of the Δ S config and δ( R B ) parameters, which is consistent with the previous results reported by Zhang et al . Nevertheless, the BSZCYYbD showed a larger V f and a smaller t .…”

supporting

confidence: 90%

High-Entropy Perovskite Electrolyte for Protonic Ceramic Fuel Cells Operating below 600 °C

Guo

2022

ACS Materials Lett.

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High-entropy materials are attracting ever-increasing concern for their unique structural features and unprecedented potential applications. In this study, we design and successfully prepared single-phase high-entropy perovskite oxide (HEPO) BaSn0.16Zr0.24Ce0.35Y0.1Yb0.1Dy0.05O3−δ (BSZCYYbD) to use as a new class of proton conductor, which is first applied to protonic ceramic fuel cells (PCFCs) below 600 °C. The BSZCYYbD exhibits excellent chemical and structural stability, high densification, and mechanical properties. The protonic conduction in BSZCYYbD is proved by the proton-conductor isotope effect and hydration effect. The protonic conductivity of BSZCYYbD is the highest ever reached in the high-entropy proton conductors, which is 8.3 mS cm–1 in humidified air (3% H2O) at 600 °C. An anode-based PCFC with BSZCYYbD electrolyte (∼45 μm) demonstrates a favorable output of 318 mW cm–2 at 600 °C. Our study offers a strategy for the design of superior proton-conducting electrolytes based on HEPOs, which hold promise for diverse electrochemical applications.

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confidence: 90%

High-Entropy Perovskite Electrolyte for Protonic Ceramic Fuel Cells Operating below 600 °C

Guo

2022

ACS Materials Lett.

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“…The elements commonly included depend on the structure type, with Co, Cu, Mg, Ni, Zn, Mn, and Cr frequently featured in rock-salt, [5,15] or spinel-type HEOs, [7,6,16,17] whereas fluorite and perovskite HEOs often contain rare-earth metals. [18][19][20][21][22] An important parameter in high-entropy materials is the entropic stabilization of the crystal structure since the free energy of mixing (ΔG mix ) decreases with an increasing entropy of mixing (ΔS mix ).…”

Section: Doi: 101002/adfm202310179mentioning

confidence: 99%

“…The elements commonly included depend on the structure type, with Co, Cu, Mg, Ni, Zn, Mn, and Cr frequently featured in rock‐salt, [ 5,15 ] or spinel‐type HEOs, [ 7,6,16,17 ] whereas fluorite and perovskite HEOs often contain rare‐earth metals. [ 18–22 ]…”

Section: Introductionmentioning

confidence: 99%

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Zander,

Wölfel,

Weiss

et al. 2023

Adv Funct Materials

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High‐entropy oxides are a material class that is currently receiving rapidly increasing attention due to the large variety in composition and the adjustable properties. Cooperative effects between different metal cations in the crystal structure in addition to entropic phase stabilization have proven beneficial for electrocatalytic applications. Most synthesis methods, however, require high synthesis temperatures and long times, and additionally only yield selected samples in good phase‐purity. Furthermore, toxic or scarce elements are often present in large amounts. Herein, a non‐aqueous microwave‐assisted solvothermal synthesis is presented as a fast and low‐temperature alternative for the fabrication of a wide range of earth‐abundant ferrites (AFe2O4). Directly crystalline, phase‐pure spinel ferrites of various compositions ranging from one to seven different A‐ions are successfully obtained after only 30 min at 225 °C. A detailed characterization of their properties in relation to their composition is performed, and they are also employed for the alkaline oxygen evolution reaction. A partial replacement of Fe by Co moreover shows the high versatility of the synthesis that also allows for the simultaneous variation of the B‐ion.

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“…Due to their high electrical conductivity, highentropy alloys are not suitable as plasma catalysts. However, the electrical conductivity of high-entropy catalyst oxides can be controlled [258][259][260]. Increasing oxygen vacancy concentration increases the carrier density and improves the conductivity of an N-type semi-conductor, and the effect is the opposite for a P-type semi-conductor [258].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, electrical conductivities could largely be controlled (enhanced or reduced) by optimizing the concentration of oxygen vacancies originating from charge compensation in other high-entropy oxides. Electrical conductivities of high-entropy garnet oxides were even lower compared to single component oxides due to the local distortion effect [260]. Similar to electrical conductivity, the introduction of chemical disorder into a compound with the addition of high-entropy metals increases the ionic conductivity through the creation of local disor-der [261].…”

Section: Introductionmentioning

confidence: 99%

Hydrogen, Ammonia and Symbiotic/Smart Fertilizer Production Using Renewable Feedstock and CO2 Utilization through Catalytic Processes and Nonthermal Plasma with Novel Catalysts and In Situ Reactive Separation: A Roadmap for Sustainable and Innovation-Based Technology

Akay

2023

Catalysts

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This multi-disciplinary paper aims to provide a roadmap for the development of an integrated, process-intensified technology for the production of H2, NH3 and NH3-based symbiotic/smart fertilizers (referred to as target products) from renewable feedstock with CO2 sequestration and utilization while addressing environmental issues relating to the emerging Food, Energy and Water shortages as a result of global warming. The paper also discloses several novel processes, reactors and catalysts. In addition to the process intensification character of the processes used and reactors designed in this study, they also deliver novel or superior products so as to lower both capital and processing costs. The critical elements of the proposed technology in the sustainable production of the target products are examined under three-sections: (1) Materials: They include natural or synthetic porous water absorbents for NH3 sequestration and symbiotic and smart fertilizers (S-fertilizers), synthesis of plasma interactive supported catalysts including supported piezoelectric catalysts, supported high-entropy catalysts, plasma generating-chemical looping and natural catalysts and catalysts based on quantum effects in plasma. Their performance in NH3 synthesis and CO2 conversion to CO as well as the direct conversion of syngas to NH3 and NH3—fertilizers are evaluated, and their mechanisms investigated. The plasma-generating chemical-looping catalysts (Catalysts, 2020, 10, 152; and 2016, 6, 80) were further modified to obtain a highly active piezoelectric catalyst with high levels of chemical and morphological heterogeneity. In particular, the mechanism of structure formation in the catalysts BaTi1−rMrO3−x−y{#}xNz and M3O4−x−y{#}xNz/Si = X was studied. Here, z = 2y/3, {#} represents an oxygen vacancy and M is a transition metal catalyst. (2) Intensified processes: They include, multi-oxidant (air, oxygen, CO2 and water) fueled catalytic biomass/waste gasification for the generation of hydrogen-enriched syngas (H2, CO, CO2, CH4, N2); plasma enhanced syngas cleaning with ca. 99% tar removal; direct syngas-to-NH3 based fertilizer conversion using catalytic plasma with CO2 sequestration and microwave energized packed bed flow reactors with in situ reactive separation; CO2 conversion to CO with BaTiO3−x{#}x or biochar to achieve in situ O2 sequestration leading to higher CO2 conversion, biochar upgrading for agricultural applications; NH3 sequestration with CO2 and urea synthesis. (3) Reactors: Several patented process-intensified novel reactors were described and utilized. They are all based on the Multi-Reaction Zone Reactor (M-RZR) concept and include, a multi-oxidant gasifier, syngas cleaning reactor, NH3 and fertilizer production reactors with in situ NH3 sequestration with mineral acids or CO2. The approach adopted for the design of the critical reactors is to use the critical materials (including natural catalysts and soil additives) in order to enhance intensified H2 and NH3 production. Ultimately, they become an essential part of the S-fertilizer system, providing efficient fertilizer use and enhanced crop yield, especially under water and nutrient stress. These critical processes and reactors are based on a process intensification philosophy where critical materials are utilized in the acceleration of the reactions including NH3 production and carbon dioxide reduction. When compared with the current NH3 production technology (Haber–Bosch process), the proposed technology achieves higher ammonia conversion at much lower temperatures and atmospheric pressure while eliminating the costly NH3 separation process through in situ reactive separation, which results in the production of S-fertilizers or H2 or urea precursor (ammonium carbamate). As such, the cost of NH3-based S-fertilizers can become competitive with small-scale distributed production platforms compared with the Haber–Bosch fertilizers.

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Preparation and electrical conductivity of (Zr, Hf, Pr, Y, La) O high entropy fluorite oxides

Cited by 31 publications

References 53 publications

High-Entropy Perovskite Electrolyte for Protonic Ceramic Fuel Cells Operating below 600 °C

High-Entropy Perovskite Electrolyte for Protonic Ceramic Fuel Cells Operating below 600 °C

Medium‐ and High‐Entropy Spinel Ferrite Nanoparticles via Low‐Temperature Synthesis for the Oxygen Evolution Reaction

Hydrogen, Ammonia and Symbiotic/Smart Fertilizer Production Using Renewable Feedstock and CO2 Utilization through Catalytic Processes and Nonthermal Plasma with Novel Catalysts and In Situ Reactive Separation: A Roadmap for Sustainable and Innovation-Based Technology

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