Solid Solution Mechanism Research Articles

Elucidating the Synergic Effect in Nanoscale MoS2 /TiO2 Heterointerface for Na-Ion Storage.

Interface engineering in electrode materials is an attractive strategy for enhancing charge storage, enabling fast kinetics, and improving cycling stability for energy storage systems. Nevertheless, the performance improvement is usually ambiguously ascribed to the "synergetic effect", the fundamental understanding toward the effect of the interface at molecular level in composite materials remains elusive. In this work, a well-defined nanoscale MoS2 /TiO2 interface is rationally designed by immobilizing TiO2 nanocrystals on MoS2 nanosheets. The role of heterostructure interface between TiO2 and MoS2 by operando synchrotron X-ray diffraction (sXRD), solid-state nuclear magnetic resonance, and density functional theory calculations is investigated. It is found that the existence of a hetero-interfacial electric field can promote charge transfer kinetics. Based on operando sXRD, it is revealed that the heterostructure follows a solid-solution reaction mechanism with small volume changes during cycling. As such, the electrode demonstrates ultrafast Na+ ions storage of 300 mAh g-1 at 10 A g-1 and excellent reversible capacity of 540 mAh g-1 at 0.2 A g-1 . This work provides significant insights into understanding of heterostructure interface at molecular level, which suggests new strategies for creating unconventional nanocomposite electrode materials for energy storage systems.

Lithium Substitution in P3-Structured Copper-Based Cathodes for Sodium-Ion Batteries

Sodium-ion batteries promise low-cost energy storage for the grid and electric vehicles, building upon the established “rocking-chair” Li-ion design, while benefitting from the natural abundance of sodium and the ability to utilize iron or copper redox reactions to further reduce the material cost. Nonetheless, Na-ion adoption has been hindered due to low energy density and large structural changes leading to poor long-term cyclability. It has been recently shown that additional reversible capacity can be obtained through oxygen redox with low voltage hysteresis in selected Na-ion layered oxide cathodes. However, the mechanisms and the intermediate species that enable this reversible oxygen redox are highly debated and not fully understood. Here we focus on several P3-structured sodium-deficient NaxY1/3Mn2/3O2 cathodes, where Y can be Cu or derivatives with partial lithium substitution, to elucidate how lithium substitution influences both the redox mechanism and the structural evolution during electrochemical cycling. Our results show a small amount (~7%) of lithium substitution can change the reaction pathway from a two-phase reaction to a solid solution mechanism, increasing stability and capacity retention. A multimodal characterization approach combining synchrotron-based X-ray spectroscopy, microscopy, and scattering techniques along with nuclear magnetic resonance spectroscopy, provides insights into the redox mechanisms, chemical species distribution, structural evolution, and phase transitions during electrochemical cycling.Acknowledgment: The work at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704. This research used resources of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Hopping Mechanism and Impedance Properties of Mg Doped NBT-KBT Solid Solution near Ambient Temperature

Solid state reaction route has been utilized to synthesize Na0.42K0.08Bi0.50Mg0.05Ti0.95O3−δ solid solution. Impedance plots are used to examine electrical attributes as a function of frequency (100 Hz –1 MHz) and temperature (10 °C–50 °C). The existence of bulk and grain boundary contributions in the impedance has been revealed by the nature of Nyquist plots. The presence of conductivity relaxation in the sample is indicated by the merging of normalized plots of modulus () profile. The ac conductivity follows Jonscher’s Power law, and suggested the correlated barrier hopping (CBH) conduction mechanism, whereas, the dc conductivity is found to be Arrhenius dependent. The activation energies computed from the conductivity and relaxation patterns are nearly identical which are 1.30 eV and 1.39 eV respectively.

Determinations of Ce solid solution mechanism and limit thermal conductivity of YTaO4 ceramics

x mol% CeO2-YTaO4 (x = 0, 3, 6, 9, 12) ceramics have been synthesized by the spark plasma sintering (SPS) technique. We focus on the changes in lattice distortion, bonding length, thermal conductivity, thermal expansion, and phase stability of the prepared samples. XRD, Raman, and XPS are used to determine the chemical valence and solid solution mechanism of Ce in the lattice of YTaO4, while its effects on thermal/mechanical properties are elucidated from microstructures. Y3+ is substituted via Ce3+, and all samples maintain a monoclinic phase. The limit thermal conductivity (1.2 W∙m−1∙K−1, 900 °C) is realized in 9 mol% CeO2-YTaO4, and the thermal expansion coefficients are increased to 10.2 × 10−6 K−1 at 1200 °C. Furthermore, the exceptional phase stability and mechanical properties of all samples indicate that they can provide good thermal insulation at high temperatures, and have higher working temperatures than the current YSZ thermal barrier coatings.

Room‐Temperature Anode‐Less All‐Solid‐State Batteries via the Conversion Reaction of Metal Fluorides

All-solid-state batteries (ASSBs) that employ anode-less electrodes have drawn attention from across the battery community because they offer competitive energy densities and a markedly improved cycle life. Nevertheless, the composite matrices of anode-less electrodes impose a substantial barrier for lithium-ion diffusion and inhibit operation at room temperature. To overcome this drawback, here, the conversion reaction of metal fluorides is exploited because metallic nanodomains formed during this reaction induce an alloying reaction with lithium ions for uniform and sustainable lithium (de)plating. Lithium fluoride (LiF), another product of the conversion reaction, prevents the agglomeration of the metallic nanodomains and also protects the electrode from fatal lithium dendrite growth. A systematic analysis identifies silver (I) fluoride (AgF) as the most suitable metal fluoride because the silver nanodomains can accommodate the solid-solution mechanism with a low nucleation overpotential. AgF-based full cells attain reliable cycling at 25 °C even with an exceptionally high areal capacity of 9.7 mAh cm-2 (areal loading of LiNi0.8 Co0.1 Mn0.1 O2 = 50mg cm-2 ). These results offer useful insights into designing materials for anode-less electrodes for sulfide-based ASSBs.

Electrochemically Active Mn-Doped Iron Hexacyanoferrate as the Cathode Material in Sodium-Ion Batteries

In this work, for the performance enhancement of iron hexacyanoferrate, an electrochemically active Mn-doped iron hexacyanoferrate cathode is fabricated via a bottom-up approach. It is found that the pre-treatment of interstitial water and appropriate Mn doping are two keys to achieving higher capacity and higher stability. The interstitial water has a trade-off effect between the alleviation of volume expansion upon Na+ (de)intercalation and the retardation of Na-ion diffusion. The moisture-tailored iron hexacyanoferrate with appropriate Mn doping exhibits a high initial Coulombic efficiency of 94.8%, enhanced capacity and rate performance, and excellent cycling stability. These results benefit from the fact that the extraction/insertion of Na ions from/into the lattice via a solid-solution mechanism correspond to both the slight volume expansion and fast sodium diffusion rate; otherwise, the removal of interstitial water and a higher Mn content might lead to poor cycling stability due to excessive volume expansion resulting from rhombohedral to cubic phase transformation. Finally, the less demand on the control of air humidity for the fabrication of electrodes and the potential for the full cell coupled with hard carbon are also demonstrated, which shows great potential for practical applications.

Formation mechanism of AlN-SiC solid solution with multiple morphologies in Al-Si-SiC composites under flowing nitrogen at 1300 °C

The non-oxide-reinforced phase AlN-SiC solid solution with high performance was successfully synthesized in the resin-bonded Al-Si-SiC composites under flowing nitrogen at 1300 °C. The AlN-SiC solid solution was synthesized by three paths of liquid-solid, gas-solid and gas-gas reactions through modulation of Al/Si ratio, and controllable microstructure of AlN-SiC solid solution was attained. The phase composition and microstructure of the sintered samples were characterized by XRD and SEM, combined with thermodynamics, the formation mechanism of AlN-SiC solid solution was investigated and the reaction model was established. Al was not detected while Si was detested by XRD. Granular, short columnar and whisker-like AlN-SiC solid solution were generated and their positions varied. As the temperature increases, the partial pressure of oxygen decreases due to the oxidation of Al, Si and SiC on the surface of the sample, inside the sample, the active oxidation takes place, generating Al2O(g), SiO(g) and CO(g). Due to the low oxygen partial pressure, Al is preferentially nitrided to form a thin AlN layer on its surface. The AlN layer is broken as the temperature increases, then liquid Al with carbon from resin begins to flow, leaving the residual shell of AlN in situ. When it flows to the surface of Si, Al-Sialloy is formed locally inside the Si particles under the wetting effect of C, then hexagonal AlN-SiC solid solution is formed inside the Si shell. Part of SiO(g) + CO(g) diffuses into the interior of the AlN residual shell and reacts by aggregation to form a granular AlN-SiC solid solution in the shell wall; others diffuses into the pores of the sample for vapor deposition, and finally forms stacked hexagonal flaky whiskers. The in-situ generated of AlN-SiC solid solution with multiple morphologies in the composite plays a joint toughening effect, which can significantly enhance the comprehensive performance of the composite. In this experiment, the synthesis of AlN-SiC solid solution without sintering aids under normal pressure at a low temperature. It is expected to be applied to the blast furnace and to realize the longevity of blast furnace.

A critical review on the microstructure and mechanical properties correlation of additively manufactured nickel-based superalloys

Inconel group of alloys, particularly IN 625 and IN 718 are the most widely recognized commercially available Ni -based superalloys employed for high temperature applications. These superalloys are known to retain their extraordinarily high strength at elevated temperatures either by solid solution or precipitation strengthening mechanisms. Consequently, they find crucial applications in the field of aerospace, automobile, and energy industries involving higher temperatures. Recently, attempts are being made to fabricate and repair the complicated superalloy components using metal additive manufacturing techniques. The ability of the additive manufacturing process to produce intricate geometry parts with greater dimensional accuracy as compared to various conventional techniques appear to be beneficial and cost-effective. However, this unique manufacturing method influences the microstructural evolution and thereby affects the performance of the IN 625 and IN 718 alloys significantly. Considering various research efforts in this direction, this article pursues a thorough review and presents a wide overview of the microstructure and mechanical properties correlation for these two additively manufactured Ni-based superalloys. • IN 625 and IN 718 alloys are the most extensively used Ni -based superalloys for various high temperature applications. • Additive manufacturing is a viable alternative to traditional methods for manufacturing these superalloy components. • The repeated heating and cooling cycles of the process alters the microstructure and mechanical performance of superalloys. • Various heat treatment schedules are designed to achieve homogenized microstructures that influences properties as well. Microstructure – property correlations for the additively manufactured IN 625 and IN 718 superalloys are explored.

Mechanical and tribological properties of WC particles reinforced Cu-20Zn matrix composites

Tungsten carbide (WC) particles can be used as reinforcement to improve the mechanical and tribological properties of metal matrix. Herein, WC reinforced Cu-20Zn matrix composites were prepared. The mechanical and tribological properties of composites were also investigated. It was confirmed that the Cu3Zn solid solution was formed during the sintering process. Due to the solid solution and load transfer strengthening mechanism, the tensile and flexural strength were significantly improved. When the WC content was 30 wt%, the tensile and flexural strength were both increased by about two times compared with Cu-20Zn alloy. Additionally, the two-body abrasive and adhesive wear were gradually weakened with increasing WC content. When the WC content was 30 wt%, the composites showed low friction coefficient and wear rate. The formation of tribo-film, which was induced by tribo-oxidation reaction, was conceived to be responsible for the favorable lubricating properties.

Reversible Intercalation of Li Ions in an Earth-Abundant Phyllosilicate Clay.

The phyllosilicate family of clays is an intriguing collection of materials that make ideal models for studying the intercalation of alkali ions due to their layered topology and broadly tunable composition space. In this spirit, we present a hydrothermal method to prepare a layered iron phyllosilicate clay, Fe2Si4O10(OH)2, and an evaluation of its electrochemical performance for the (de)insertion of Li ions. Through careful structural refinement, we determined that this iron clay contains a 2:1 stacking sequence, which is directly analogous to the widely studied mineral montmorillonite, with the crystallites adopting a platelike morphology. Cyclic voltammetry and galvanostatic cycling reveal reversible insertion of lithium into the interstitial layers via a solid solution mechanism. Comparison of ion (de)intercalation with reports on other clay systems like muscovite, KFe2.75Si3.25O10(OH)2, which features a rigidly bound interlayer cation, demonstrates that controlling the net charge on the layers with phyllosilicate minerals is a route to enabling reversible cationic intercalation within the structure.

All-climate and air-stable NASICON-Na2TiV(PO4)3 cathode with three-electron reaction toward high-performance sodium-ion batteries

• The three-electron Na 2 TiV(PO 4 ) 3 delivers 187 mA h g −1 . • NTVP/C-G demonstrates ideal all-climate and air-stable performances. • In-situ XRD shows that NTVP involves Δ volume of 4.9%. • DFT calculations reveal low band gap and low energy barrier of 0.2 eV in NTVP. Developing all-climate and air-stable cathode with multi-electron redox reaction is intriguing and challenging for sodium-ion batteries (SIBs). Herein, we synthesize a NASICON (Na super-ionic conductor)-type Na 2 TiV(PO 4 ) 3 with an elaborately-engineered architecture, which shows ultrastable (1000 cycles at 40C) and ultrafast (up to 40C) three-sodium storage performances with an ultrahigh capacity of 187 mA h g −1 (equals to theoretical value) at 0.1C. Also, it displays good air-stability and high/low-temperature properties. A series of stepwise solid-solution, two-phase, solid-solution and two-phase mechanisms are involved and a small volume change of 4.9% is identified according to the operando X-ray diffraction results. Ex situ X-ray photoelectron spectroscopy reveals that V 4+ /V 3+ , Ti 4+ /Ti 3+ and V 3+ /V 2+ redox reactions are accompanied with three-sodium storage processes. The small band gap of 1.48 eV and fast 3D Na + diffusion pathways with low energy barrier of 0.2 eV calculated through first-principles calculations are responsible for the superior electrochemical performances. Our work prepares Na 2 TiV(PO 4 ) 3 with three-electron redox and high performance for future practical SIBs applications.

Enthalpy driving force and chemical bond weakening: The solid-solution formation mechanism and densification behavior of high-entropy diborides (Hf1−x/4Zr1−x/4Nb1−x/4Ta1−x/4Scx)B2

(Hf0.2Zr0.2Nb0.2Ta0.2Sc0.2)B2 was designed to improve the densification and solid-solution formation of high-entropy transition metal diborides, and its phase stability was predicted using the energy distribution of the local mixing enthalpy of all possible configurations. It was found that (Hf0.2Zr0.2Nb0.2Ta0.2Sc0.2)B2 are enthalpy-stabilized materials. The two-component metal diborides formed by transition metal diborides (HfB2, ZrB2, TaB2 and NbB2) with ScB2 are thermodynamically favorable, based on the mixing enthalpy. Therefore, the introduction of ScB2 in high-entropy metal diborides is beneficial to reduce the mixing Gibbs free energy during the boro/carbothermal reduction process, which enables the formation of single-phase solid solution at low temperatures. Even high-entropy metal diboride powders with large particle sizes, 25–57 µm, can achieve sintered density up to ~97% due to the introduction of ScB2 in high-entropy metal diborides, owing to its weakening action on the TM d - B p and the TM dd bonding.

Phase composition and its effect on the mechanical performance of an AlCoCrFeNiTi high-entropy alloy

The concept of High-Entropy Alloy (HEA) expanded the research field of advanced metallic materials for various applications, like the development of ultra-hardness ballistic protection materials for national security. Although there can be hundreds of compositions, carefully selecting the constituent is mandatory to improve their mechanical behavior, keeping in mind their microstructural array based on chemical composition. In the present study, the AlCoCrCuFeNi HEA was modified, replacing copper with titanium, looking for the formation of a Ti-rich BCC phase for hardening effects. Samples were prepared following the powder metallurgy route, including mechanical alloying favoring the generation of a nanocrystalline microstructure. Studies based on structure, microstructure and nanoindentation testing on each phase of the alloy were performed to determine the correlation between their composition, crystalline structure and mechanical properties. Evidence showed the formation of three main micrometric phases (two BCC and one tetragonal) coexisting with a nanometric dispersion of rounded precipitates. Nanoindentation testing shows that the main hardening effect was related to the tetragonal phase formation by a solid-solution strengthening mechanism. This phase reached the highest hardness (14.9 GPa); meanwhile, the richest Ti phase showed the lowest elastic modulus, titanium favors the material ductility.

NASICON-structured Na3MnTi(PO4)2.83F0.5 cathode with high energy density and rate performance for sodium-ion batteries

NASICON-structured materials with high ionic conductivity, robust structure, and high operation potential have aroused extensive attentions as cathode for sodium-ion batteries (SIBs). However, the poor intrinsic electronic conductivity and low specific capacity are crucial obstacles for practical application of NASICON materials. Herein, a new NASICON-structured Na3MnTi(PO4)2.83F0.5 (NMTPF-0.5) with the hierarchical and porous structure is synthesized by a simple sol–gel method. The Rietveld refinements and Inductively Coupled Plasma (ICP) chemical analysis confirms the NASICON structure of NMTPF-0.5. The unique structural design significantly enhances rate performance. Meanwhile, the introduction of F- stimulates electrochemical activities of Mn, and stabilizes crystal structure compared with traditional Na3MnTi(PO4)3. Consequently, the NMTPF-0.5 achieves the high energy density of 511 Wh kg−1 at 0.1C, an outstanding rate performance (364 Wh kg−1 at 10C), and the desirable cycling stabilities exceeding 500 cycles at 10C. The ex-situ XRD reveals the insertion/extraction of Na+ through the reversible solid-solution mechanism. Moreover, we statistically analyze how the electrochemical properties and microstructure affected by various F- substitution amounts. This study explored a novel strategy for designing high capacity and high power-density cathode materials for SIBs via the microstructure and crystal structure optimization.

Lattice-Resolution, Dynamic Imaging of Hydrogen Absorption into Bimetallic AgPd Nanoparticles.

Palladium's strong reactivity and absorption affinity to H2 makes it a prime material for hydrogen-based technologies. Alloying of Pd has been used to tune its mechanical stability, catalytic activity, and absorption thermodynamics. However, atomistic mechanisms of hydrogen dissociation and intercalation are informed predominantly by theoretical calculations, owing to the difficulty in imaging dynamic metal-gas interactions at the atomic scale. Here, we use in situ environmental high resolution transmission electron microscopy to directly track the hydrogenation-induced lattice expansion within AgPd triangular nanoprisms. We investigate the thermodynamics of the system at the single particle level and show that, contrary to pure Pd nanoparticles, the AgPd system exhibits α/β coexistence within single crystalline nanoparticles in equilibrium; the nanoparticle system also moves to a solid-solution loading mechanism at lower Ag content than bulk. By tracking the lattice expansion in real time during a phase transition, we see surface-limited β phase growth, as well as rapid reorientation of the α/β interface within individual particles. This secondary rate corresponds to the speed with which the β phase can restructure and, according to our atomistic calculations, emerges from lattice strain minimization. We also observe no preferential nucleation at the sharpest nanoprism corners, contrary to classical nucleation theory. Our results achieve atomic lattice plane resolution─crucial for exploring the role of crystal defects and single atom sites on catalytic hydrogen splitting and absorption.

Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd2Zr2O7 thermal barrier coatings: Theoretical and experimental studies

Sc was doped into Gd2Zr2O7 for expanding the potential for thermal barrier coating (TBC) applications. The solid solution mechanism of Sc in the Gd2Zr2O7 lattice, and the mechanical and thermophysical properties of the doped Gd2Zr2O7 were systematically studied by the first-principles method, based on which the Sc doping content was optimized. Additionally, Sc-doped Gd2Zr2O7 TBCs with the optimized composition were prepared by air plasma spraying using YSZ as a bottom ceramic coating (Gd-Sc/YSZ TBCs), and their sintering behavior and thermal cycling performance were examined. Results revealed that at low Sc doping levels, Sc has a large tendency to occupy the lattice interstitial sites, and when the doping content is above 11.11 at%, Sc substituting for Gd in the lattice becomes dominant. Among the doped Gd2Zr2O7, the composition with 16.67 at% Sc content has the lowest Pugh’s indicator (G/B) and the highest Poisson ratio (σ) indicative of the highest toughness, and the decreasing trends of Debye temperature and thermal conductivity slow down at this composition. By considering the mechanical and thermophysical properties comprehensively, the Sc doping content was optimized to be 16.67 at%. The fabricated Gd-Sc coatings remain phase and structural stability after sintering at 1400 °C for 100 h. Gd-Sc/YSZ TBCs exhibit excellent thermal shock resistance, which is related to the good thermal match between Gd-Sc and YSZ coatings, and the buffering effect of the YSZ coating during thermal cycling. These results revealed that Sc-doped Gd2Zr2O7 has a high potential for TBC applications, especially for the composition with 16.67 at% Sc content.

Operando Electrochemical X-ray Diffraction and Raman Spectroscopic Studies Revealing the Alkali-Metal Ion Intercalation Mechanism in Prussian Blue Analogues.

Prussian blue analogues are promising cathode material candidates for aqueous rechargeable metal-ion batteries. Although great efforts have been made on developing materials, there are still rare reports on optimizing cell performance from mechanistic understanding and studies. Here we unveil the alkali-metal-ion intercalation mechanism in Berlin green with a home-built spectroelectrochemical cell for operando X-ray Diffraction (XRD) and Raman spectroscopies, which allows us to obtain the correlated local structure, crystal structure, redox activity, and potential profiles during the charging and discharging processes. We found that the intercalation of Na+ follows a solid solution mechanism leading to a high capacity, and the intercalation of K+ follows a two-phase transition mechanism showing a high voltage. With this understanding, we propose a new strategy using a Na+/K+ hybrid cation electrolyte to realize both high voltage and energy density. This study offers a unique insight for improving the cell performance from the understanding of the reaction mechanism.

Effect of Fe2O3–TiO2-Sm2O3 composite additive on sintering behavior and thermal properties of Al2O3 ceramics for thermal storage

Al2O3 ceramics were prepared by introducing Fe2O3–TiO2-Sm2O3 composite additive, in which the content and ratios of Fe2O3 and TiO2 remained constant, but Sm2O3 was variable. The phase transformation, micromorphology, physical properties and thermal properties were investigated. The results showed that Fe2O3 and TiO2 made the grains high sintering activity through a solid solution mechanism, which promoted grain growth, but Sm2O3 preferred to form SmFe4Al8O19 at the grain boundaries, which slowed grain growth and refined the grains. With the increase in Sm2O3, the grain refinement of SmFe4Al8O19 became outstanding, and the grain diameter gradually decreased, which is favorable for denser sintering. However, only a proper amount of Sm2O3 in the Fe2O3–TiO2-Sm2O3 composite additive resulted in better thermal shock resistance. The Al2O3 ceramics with 9 wt% Fe2O3-1 wt% TiO2-5 wt% Sm2O3 sintered at 1520 °C exhibited the optimum properties, yielding an increase in the bending strength by 6.60% after 30 thermal shocks, a thermal conductivity of 13.33–5.64 W/(m·K) (25–800 °C) and a specific heat capacity of 0.94–1.25 J/(g·K) (25–800 °C), all of which demonstrate the potential for thermal storage.

Phase decomposition and strengthening in HfNbTaTiZr high entropy alloy from first-principles calculations

Phase decomposition influences significantly the mechanical properties of high entropy alloys (HEAs). Prediction of the phase decomposition of HEA is greatly hindered by the hyper-dimensional composition space of the alloys. In the present work, we propose to represent the HEAs as various pseudo-binary alloys of which the temperature dependent free energies as functions of compositions may be readily calculated by using first-principles methods in combination with thermodynamic models. With the calculated free energies, the phase diagrams of the pseudo-binary alloys may be constructed and the phase decomposition can be predicted. This procedure is applied to Hf-Nb-Ta-Ti-Zr alloy with body-centered cubic (BCC) structure. We predict that the equiatomic HfNbTaTiZr HEA suffers from phase decomposition below critical temperature of 1298 K. The HEA decomposes most favorably to BCC NbTa-rich and HfZr-rich phases. The BCC HfZr-rich phase transfers to a hexagonal close-packed structure (HCP) phase at low temperature. The predicted compositions of the decomposed phases are in good agreement with experiment and Thermal-Calc modeling. Furthermore, the effect of the phase decomposition on the strength of the HEA is evaluated by considering the solid-solution and precipitation strengthening mechanisms. The precipitation strengthening effect is stronger than the solid-solution strengthening at the low annealing temperature but becomes weaker at high annealing temperature.

Insights into the promotion mechanism of ceria-zirconia solid solution to ethane combustion over Pt-based catalysts

Pt/Ce0.5Zr0.5O2 (denoted as Pt/CZ11) and Pt/Al2O3 with identical Pt loading and dispersion were prepared and evaluated for ethane catalytic combustion. Pt/CZ11 exhibited higher activity than Pt/γ-Al2O3 even with similar Pt dispersion. Combined with various characterizations, it was revealed that the enrichments of surface active oxygen and oxygen vacancy on Pt/CZ11 facilitated ethane combustion owing to the strong interaction between Pt and Ce-Zr solid solution. Moreover, in situ DRIFT results demonstrated that different reaction mechanisms were followed over Pt/CZ11 and Pt/Al2O3. The front followed the single-site Langmuir-Hinshelwood (L-H), in which C2H6 and O2 were absorbed and activated on Pt sites. While the coupled reaction mechanism involving L-H and Mars-van Krevelen (MvK) were illustrated over Pt/CZ11, on which ethane can be activated on Pt sites and CZ11 support. More mechanistic insights into ethane combustion provided the guidelines for the developments of catalysts with superior performance for light-carbon alkane volatile organic compounds.