Extended damage range of(Al0.3Cr0.2Fe0.2Ni0.3)3O4 high entropy oxide films induced by surface irradiation

Irradiation makes structural materials of nuclear reactors degraded and failed.However,the damage process of materials induced by irradiation is not fully elucidated,mostly because the charged particles only bombarded the surface of the materials(within a few microns).In this work,we investigated the effects of surface irradiation on the indirect irradiation region of the(Al0.3Cr0.2Fe0.2Ni0.3)3O4 high entropy oxide(HEO)films in detail by plasma surface interaction.The results show that the damage induced by surface irradiation significantly extends to the indirect irradiation region of HEO film where the helium bubbles,dislocations,phase transformation,and the nickel oxide segregation were observed.

Boron-doped high-entropy oxide toward high-rate and long-cycle layered cathodes for wide-temperature sodium-ion batteries

03-type layered metal oxides hold great promise for sodium-ion batteries cathodes owing to their energy density advantage.However,the severe irreversible phase transition and sluggish Na^(+)diffusion kinetics pose significant challenges to achieve high-performance layered cathodes.Herein,a boron-doped03-type high entropy oxide Na(Fe_(0.2)Co_(0.15)Cu_(0.05)Ni_(0.2)Mn_(0.2)Ti_(0.2))B_(0.02)O_(2)(NFCCNMT-B_(0.02))is designed and the covalent B-O bonds with high entropy configuration ensure a robust layered structure.The obtained cathode NFCCNMT-B_(0.02)exhibits impressive cycling performance(capacity retention of 95%and 82%after100 cycles and 300 cycles at 1 and 10 C,respectively)and outstanding rate capability(capacity of 83 mAh g^(-1)at 10 C).Furthermore,the NFCCNMT-B_(0.02)demonstrates a superior wide-temperature performance,maintaining the same capacity level(113,4 mAh g^(-1)@-20℃,121 mAh g^(-1)@25℃,and 119 mAh g^(-1)@60℃)and superior cycle stability(90%capacity retention after 100 cycles at 1 C at-20℃).The high-entropy configuration design with boron doping strategy contributes to the excellent sodium-ion storage performance.The high-entropy configuration design effectively suppresses irreversible phase transitions accompanied by small volume changes(ΔV=0.65 A3).B ions doping expands the Na layer distance and enlarges the P3 phase region,thereby enhancing Na^(+)diffusion kinetics.This work offers valuable insights into design of high-performance layered cathodes for sodium-ion batteries operating across a wide temperature.

Facile synthesis of nanosized spinel high entropy oxide (FeCoNiCrMn)_(3)O_(4) for efficient oxygen evolution reaction

The sluggish reaction kinetics of oxygen evolution reaction(OER)and the high price of noble metal catalysts hinder the wide application of water electrolysis for hydrogen generation.High-entropy oxides(HEOs)with multi-components and high entropy stabilized structures have attracted great research interests due to their efficient and durable performance in electrolytic water splitting reactions.However,the development of efficient HEO electrocatalysts are often hindered by the limited surface exposed active sites because high temperature is usually required to form a high entropy stabilized structure.Herein,a flaky high-entropy oxide with a spinel structure,(FeCoNiCrMn)_(3)O_(4),was synthesized by using the sacrificial layered carbon template in situ prepared by the volatile reaction between ammonium sulfate and molten glucose.High-resolution TEM results show the as-prepared(FeCoNiCrMn)_(3)O_(4) flakes are composed of nanosized HEO particles.The nanosized(FeCoNiCrMn)_(3)O_(4) HEO electrocatalysts exhibit excellent OER activity,with an overpotential of 239 mV at 10 mA/cm^(2) and a Tafel slope of 52.4 mV/dec.The electrocatalyst has excellent stability.Even at a high current density of 100 mA/cm^(2),the activity remains unchanged during the stability test for 24 h.The results here shed a new light in the design and fabrication of highly efficient HEO electrocatalysts.

Titanium-containing high entropy oxide(Ti-HEO):A redox expediting electrocatalyst towards lithium polysulfides for high performance Li-S batteries

Since lithium sulfur(Li-S)energy storage devices are anticipated to power portable gadgets and electric vehicles owing to their high energy density(2600 Wh·kg^(-1));nevertheless,their usefulness is constrained by sluggish sulfur reaction kinetics and soluble lithium polysulfide(LPS)shuttling effects.High electrically conductive bifunctional electrocatalysts are urgently needed for Li-S batteries,and high-entropy oxide(HEO)is one of the most promising electrocatalysts.In this work,we synthesize titanium-containing high entropy oxide(Ti-HEO)(TiFeNiCoMg)O with enhanced electrical conductivity through calcining metal-organic frameworks(MOF)templates at modest temperatures.The resulting single-phase Ti-HEO with high conductivity could facilitate chemical immobilization and rapid bidirectional conversion of LPS.As a result,the Ti-HEO/S/KB cathode(with 70 wt.%of sulfur)achieves an initial discharge capacity as high as~1375 mAh·g^(-1)at 0.1 C,and a low-capacity fade rate of 0.056%per cycle over 1000 cycles at 0.5 C.With increased sulfur loading(~5.0 mg·cm^(-2)),the typical Li-S cell delivered a high initial discharge capacity of~607 mAh·g^(-1)at 0.2 C and showcased good cycling stability.This work provides better insight into the synthesis of catalytic Ti-containing HEOs with enhanced electrical conductivity,which are effective in simultaneously enhancing the LPS-conversion kinetics and reducing the LPS shuttling effect.

Activating surface atoms of high entropy oxides for enhancing oxygen evolution reaction

High entropy oxides(HEOs) have attracted extensive attention of researchers due to their remarkable properties. The electrocatalytic activity of electrocatalysts is closely related to the reactivity of their surface atoms which usually shows a positive correlation. Excellenet stability of HEOs leads to their surface atoms with relative poor reactivity, limiting the applications for electrocatalysis. Therefore, it is significant to activate surface atoms of HEOs. Constructing amorphous structure, introducing oxygen defects and leaching are very effective strategies to improve the reactivity of surface atoms. Herein, to remove chemical inert, low-crystallinity(Fe, Co, Ni, Mn, Zn)_(3)O_(4) (HEO-Origin) nanosheets with abundant oxygen vacancies was synthesized, showing an excellent catalytic activity with an overpotential of 265 mV at 10 mA/cm^(2), which outperforms as-synthesized HEO-500℃-air(335 mV). The excellent catalytic performance of HEO-Origin can be attributed to high activity surface atoms, the introduction of oxygen defects efficiently altered electron distribution on the surface of HEO-Origin. Apart from, HEO-Origin also exhibits an outstanding electrochemical stability for oxygen evolution reaction(OER).

Rh-loaded High-entropy Oxide for Efficiently Catalyzing the Reverse Water-Gas Shift Reaction

Establishing efficient CO_(2) hydrogenation technology based on the reverse water-gas shift (RWGS) reaction can effectively alleviate environmental problems while providing high-value-added products.The development of suitable advanced supports is the key to improving the catalytic activity and selectivity.Herein,we designed and synthesized a new type of spinel-phase high entropy oxides [(FeCrMnAlGa)3O4-x,FMG],which exhibited remarkable RWGS performance after loading small-size Rh nanoparticles.The CO yield was as high as 145.5 μmolCO·gcat^(-1)·s^(-1) at 380 ℃ and the CO selectivity was nearly 100%.Moreover,the catalyst retained over 95% of the initial activity after 25 h of continuous catalyzing.Experimental and structural studies reveal that the FMG support has elemental synergy and high-entropy stability,which affect the Rh dispersion and oxygen vacancy generation,in turn achieving superior catalytic performance.

High-entropy oxides as energy materials:from complexity to rational design

High-entropy oxides(HEOs),with their multi-principal-element compositional diversity,have emerged as promising candidates in the realm of energy materials.This review encapsulates the progress in harnessing HEOs for energy conversion and storage applications,encompassing solar cells,electrocatalysis,photocatalysis,lithium-ion batteries,and solid oxide fuel cells.The critical role of theoretical calculations and simulations is underscored,highlighting their contribution to elucidating material stability,deciphering structure-activity relationships,and enabling performance optimization.These computational tools have been instrumental in multi-scale modeling,high-throughput screening,and integrating artificial intelligence for material design.Despite their promise,challenges such as fabrication complexity,cost,and theoretical computational hurdles impede the broad application of HEOs.To address these,this review delineates future research perspectives.These include the innovation of cost-effective synthesis strategies,employment of in situ characterization for micro-chemical insights,exploration of unique physical phenomena to refine performance,and enhancement of computational models for precise structure-performance predictions.This review calls for interdisciplinary synergy,fostering a collaborative approach between materials science,chemistry,physics,and related disciplines.Collectively,these efforts are poised to propel HEOs towards commercial viability in the new energy technologies,heralding innovative solutions to pressing energy and environmental challenges.

High-entropy chemistry stabilizing spinel oxide(CoNiZnXMnLi)_(3)O_(4)(X=Fe,Cr)for high-performance anode of Li-ion batteries

High entropy oxides(HEOs),as a new type of single-phase multielement solid solution materials,have shown many attractive features and promising application prospect in the energy storage fleld.Herein,six-element HEOs(CoNiZnFeMnLi)_(3)O_(4) and(CoNiZnCrMnLi)_(3)O_(4) with spinel structure are successfully prepared by con-ventional solid-phase method and present outstanding lithium storage performances due to the synergy effect of various electrochemically active elements and the entropy stabilization.By contrast,(CoNiZnFeMnLi)_(3)O_(4) delivers higher initial discharge specific capacity of 1104.3 mAh·g^(−1),better cycle stability(84%capacity retention after 100 cycles at 100 mA·g^(−1)) and rate performance(293 mAh·g^(−1)at 2000 mA·g^(−1))in the half-cell.Moreover,the full-cell assembled with(CoNiZnFeMnLi)_(3)O_(4) and LiCoO_(2)provides a reversible specific capacity of 260.2 mAh·g^(−1)after 100 cycles at 500 mA·g^(−1).Ex situ X-ray diffraction reveals the electrochemical reaction mechanism of HEOs(CoNiZnFeMnLi)_(3)O_(4),and the amorphous phase and the large amount of oxygen vacancies were obtained after the initial discharge process,which are responsible for the excellent cycle and rate performance.This research puts forward fresh insights for the development of advanced energy storage materials for high-performance batteries.

Entropy-driven phase regulation of high-entropy transition metal oxide and its enhanced high-temperature microwave absorption by in-situ dual phases

High-temperature microwave absorbers are significant for military equipment which experiences severe aerodynamic heat.In this work,high-entropy oxide(HEO)(FexCoNiCrMn)mOn with excellent high-temperature microwave absorption is studied.Driven by the effect of entropy,the composition of the oxide can be transformed from spinel-type phase(FexCoNiCrMn)_(3)O_(4) to corundum-type phase(FexCoNiCrMn)2O3 with the increasing content of iron.Only spinel-type or corundum-type structure composes the oxide when x≤3 or x≥5.But in-situ dual phases can coexist when x equals 4 during phase transition.Interestingly,obliged to abundant heterogeneous interfaces and crystal defects in the dual-phase HEO,magnetic property,dielectric polarization,and microwave loss ability are all well enhanced.The Smith chart analysis demonstrates the impedance matching condition is well improved due to the enhanced loss ability.These findings pave a new way for the adjustment of electromagnetic properties of HEO by entropy-driven phase regulation.Meanwhile,the dual-phase absorber can achieve better than 90%absorption in 9.6-12.4 GHz at 800℃ with a thickness of 2.6 mm,a low thermal diffusivity of 0.0038 cm^(2)/s at 900℃,and excellent high-temperature stability,which indicates it’s promising as a high-temperature microwave absorber.

Optical properties and irradiation resistance of novel high-entropy oxide glasses La_(2)O_(3)-TiO_(2)-Nb_(2)O_(5)-WO_(3)-M_(2)O_(3)(M=B/Ga/In)

A new class of high-entropy oxide glasses 20LaO_(3/2)-20TiO_(2)-20NbO_(5/2)-20WO_(3)-20MO_(3/2)(M=B/Ga/In)were designed and successfully fabricated by aerodynamic containerless processing.The results show that one can control the properties and increase the functionality of glass by changing the type of M.The Vicker's hardness reaches the highest value of 6.45 GPa for glass M=B.The best thermal stability and the glass forming ability,measured using the glass-transition temperature T_(g) and the temperature gap ΔT respectively,are found in glass M=In,with T_(g)=740℃ and ΔT=72℃.The optical properties show that the as-prepared glasses exhibit good transparency and high refractive index.Especially for glass M=In,its transmittance reaches almost 78% from visible to IR region,and the value is nearly unchanged after electron beam irradiation,indicating good irradiation resistance of this high-entropy oxide glass.Furthermore,the glass M=In has the highest refractive index(n_(d)=2.46) and low wavelength dispersion(v_(d)=45.6).These results demonstrate that the conceptual design of high-entropy materials is adaptable to high performance oxide glasses,which should be promising host materials for optical applications such as smart phones with digital cameras and endoscopes.