Search

Solid oxide electrolysis cell (SOEC) is a promising technology for CO2 conversion and renewable energy storage with high efficiency. It is highly desirable to develop catalytically active cathodes for CO2 electrolysis. Herein, cathode materials with different structural stabilities are designed by Nb substitution on La0.5Sr0.5Fe0.8Co0.2O3-δ (LSFC82) to obtain La0.5Sr0.5Fe0.7Co0.2Nb0.1O3-δ (LSFCN721) and La0.5Sr0.5Fe0.8Co0.1Nb0.1O3-δ (LSFCN811), respectively. LSFC82-Sm0.2Ce0.8O2-δ (SDC) cathode with inferior structural stability (ability to maintain the structure) shows desirable CO2 electrolysis performance with the generated current density of 1.80 A cm−2 at 1.6 V and stable performance during 110 h operation at 1.2 V and 800 °C. However, LSFC82 particles are collapsed into pieces after stability test with the generation of Co nanoparticles simultaneously. The frameworks of LSFCN721 and LSFCN811 particles maintain well because of the high-valent niobium, but Co exsolution, oxygen vacancy content and the corresponding CO2 electrolysis performance are restricted. This work confirms that Co nanoparticles can be exsolved from LSFC82-SDC cathode during CO2 electrolysis, providing references for constructing metallic nanoparticles decorated-perovskite cathodes for SOECs.

Abstract Elemental vacancies are proposed as an effective approach to tuning the electronic structure of catalysts that are critical for energy conversion. However, for reactions such as the sluggish oxygen evolution reaction, the excess of oxygen vacancies (VO) is inevitable and detrimental to catalysts’ electrochemical stability and activities, e.g., in the most active RuO2. While significant work is carried out to hinder the formation of VO, the development of a fast and efficient strategy is limited. Herein, a protection SrO layer produced successfully at the surface of RuO2 with the in situ exsolution method with perovskite SrRuO3 as the precatalyst, which could significantly hinder the generation of VO. Benefited from the suppression of VO, the surface‐modified RuO2 requires a low overpotential of 290 mV at 100 mA cm−2, accompanied by remarkably high electrochemical stability (100 h) and Faraday efficiency (≈100%). Theoretical investigation reveals that the formation energy of VO in RuO2 is almost doubled in the exsolved RuO2 phase as a result of the weakened RuO bond covalency. This work not only provides insight into the structural evolution of perovskite oxide catalysts but also demonstrates the feasibility of controlling vacancy formation via in situ exsolution.

Abstract The benefits of perovskite oxides include their low cost, customizable composition, ordered atomic structure, and extremely flexible electronic structure. They are the ideal substitute for precious metal catalysts in various electrocatalytic reactions. However, the initial activity of perovskite oxides is often quite limited, which is extremely related to their crystal structure and electronic structure. In this regard, component regulation is the simplest and most effective strategy to increase their stability and catalytic activity. In this review, we briefly outline the recent progress in the modulating component of perovskite oxides to enhance their catalytic properties. The outline was categorized according to the sites in the ABO3‐type perovskite structure, including A‐site, B‐site, and O‐site regulation. Finally, potential research directions aimed at modulating of perovskite oxide constituents are discussed.

A Mn0.2Zr0.8O2−δ mixed oxide catalyst was synthesized via the co-precipitation method and studied in a CO oxidation reaction after different redox pretreatments. The surface and structural properties of the catalyst were studied before and after the pretreatment using XRD, XANES, XPS, and TEM techniques. Operando XRD was used to monitor the changes in the crystal structure under pretreatment and reaction conditions. The catalytic properties were found to depend on the activation procedure: reducing the CO atmosphere at 400–600 °C and the reaction mixture (O2 excess) or oxidative O2 atmosphere at 250–400 °C. A maximum catalytic effect characterized by decreasing T50 from 193 to 171 °C was observed after a reduction at 400 °C and further oxidation in the CO/O2 reaction mixture was observed at 250 °C. Operando XRD showed a reversible reduction-oxidation of Mn cations in the volume of Mn0.2Zr0.8O2−δ solid solution. XPS and TEM detected the segregation of manganese cations on the surface of the mixed oxide. TEM showed that Mn-rich regions have a structure of MnO2. The pretreatment caused the partial decomposition of the Mn0.2Zr0.8O2−δ solid solution and the formation of surface Mn-rich areas that are active in catalytic CO oxidation. In this work it was shown that the introduction of oxidation-reduction pretreatment cycles leads to an increase in catalytic activity due to changes in the origin of active states. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 into valuable fuels and chemicals has become a contemporary research area, where the heterogeneous catalyst plays a critical role. Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation. Here, we review the CO2 reduction with active materials prepared by exsolution. The fundamental of exsolution was summarized in terms of mechanism and models, materials, and driven forces. The advances in the exsolved materials used in hightemperature CO2 electrolysis were catalogued into tailored interfaces, synergistic effects on alloy particles, phase transition, reversibility and electrochemical switching. [ABSTRACT FROM AUTHOR]

Oxidative coupling of methane (OCM) can be performed electrocatalytically by utilizing solid oxide cells, which provide a readily controlled oxygen supply through dense electrolytes. La0.7Sr0.2Ni0.2Fe0.8O3 (LSNF) perovskite is an effective anode for OCM. Its surface characteristics and electrocatalytic activity can be improved by reduction and the resultant exsolution of bimetallic NiFe nanoparticles from its bulk. X‐ray diffraction (XRD) and environmental transmission electron microscopy proved that the evolution of hetero‐phases under reducing environment resulted in bimetallic NiFe nanoparticles being formed on the surface. A 36 % improvement in C2+ hydrocarbon production rate was achieved due to the reduction of LSNF with the exsolved NiFe nanoparticles. Co‐feeding of H2O enhanced selective conversion of CH4 resulting in the production rate of C2+ hydrocarbons being increased by 56 %. Analysis of impedance spectra and in‐situ DRIFTS under a CH4+H2O atmosphere provided an understanding for the enhancement on the electrocatalytic OCM. [ABSTRACT FROM AUTHOR]

A large proportion of the critical elements resources Ge, Ga, and In are associated with sphalerite in Pb-Zn ore deposits. Germanium in sphalerite has been proposed to be structurally bound in the crystal lattice. Using a combination of microstructural, geochemical and nanoscale observations, we show that Ge can be hosted in sphalerite crystal structure as well as nanoparticles of briartite (Cu 2 (Zn,Fe)GeS 4). The structurally-bound Ge was preserved in undeformed sphalerite grains from the Saint-Salvy Pb-Zn vein deposit (France), whereas the briartite nanoparticles were observed in metamorphosed sphalerite from Arre. The briartite nanoparticles likely exsolved from sphalerite during the Pyrenean-Alpine metamorphism and deformation. The presence of nanoparticles may harden the sphalerite during crystal-plastic deformation and help to preserve the critical elements resources of Pb-Zn deposits during metamorphism. [ABSTRACT FROM AUTHOR]

Hydrogen production from biogas over alumina-supported Ce1−xNixO2−x catalysts was studied in a temperature range of 600–850 °C with an initial gas composition of CH4/CO2/H2O of 1/0.8/0.4. To achieve a high and stable hydrogen yield, highly dispersed Ni catalysts were prepared through the exsolution approach. A solid solution of Ce1−xNixO2−x was firstly formed on the surface of Al2O3 and then activated in H2/Ar at 800 °C. The genesis and properties of the Ce1−xNixO2−x/Al2O3 catalysts were established using X-ray fluorescence analysis, thermal analysis, N2 adsorption, ex situ and in situ X-ray diffraction, Raman spectroscopy, electron microscopy, EDX analysis, and temperature-programmed hydrogen reduction. The performance of Ce1−xNixO2−x/Al2O3 catalysts in biogas conversion was tuned by regulation of the dispersion and reducibility of the active component through variation of content (5–20 wt.%) and composition (x = 0.2, 0.5, 0.8) of Ce1−xNixO2−x as well as the mode of its loading (co-impregnation (CI), citrate sol–gel method (SG)). For the 20 wt.% Ce1−xNixO2−x/Al2O3 catalyst, the rate of the coke formation decreased by a factor of 10 as x increased from 0.2 to 0.8. The optimal catalyst composition (20 wt.% Ce0.2Ni0.8O1.8/80 wt.% Al2O3) and preparation mode (citrate sol–gel method) were determined. At 850 °C, the 20 wt.% Ce0.2Ni0.8O1.8/Al2O3-SG catalyst provides 100% hydrogen yield at full CH4 conversion and 85% CO2 utilization. [ABSTRACT FROM AUTHOR]

The escalating increase in global temperatures has highlighted hydrogen (H 2) as a promising alternative clean energy carrier. Hydrogen can be derived from biofuels such as bioethanol, offering an efficient liquid carrier that addresses availability, storage, and distribution issues hindering a widespread use of H 2. This study reports on the synthesis of La 0.4 Sr 0.4 Ti 0.8 Ni 0.2 O 3-δ catalysts followed by the exsolution process to enhance catalytic activity for H 2 production via ethanol steam reforming (ESR) reaction. Single-phase compounds with exsolved metallic nanoparticles were successfully tested for ESR, revealing an ethanol conversion rate of 40 % and over 40 % H 2 production for the catalyst reduced at 1000 °C for 12 hours. Stability tests demonstrated the catalyst's capacity for regeneration in both water vapor and N 2. The experimental data demonstrate that exsolving metallic nanoparticles is a viable strategy for producing a stable catalyst for the ESR reaction. • Ni exsolution in lanthanun-titanate perovskite was studied for ethanol reforming. • Temperature and time of exsolution influenced size and number per unit area of Ni0 particles. • Catalysts exsolved at 1000 °C for 12 hours showed 40 % H 2 production at 600 °C. • The catalyst can be regenerated in water vapor and N 2. [ABSTRACT FROM AUTHOR]

An effective strategy for CO 2 electrolysis by solid oxide electrolysis cells (SOECs) is to design high-performance cathode material by interface engineering. In this work, a Ni-doped Sr 0.95 Ti 0.3 Fe 0.7 O 3-δ /Ce 0.9 Gd 0.1 O 2-δ (denoted as STFN/GDCN) nanofiber composite is directly obtained via electrospinning. Then, Ni nanoparticles are dual-exsolved by 10%H 2 /Ar reduction to in-situ anchor on the surface of STFN and GDCN (denoted as Ni@STFN/GDCN), which is used as SOECs cathode. This developed composite cathode not only facilitates CO 2 reduction reaction (CO 2 RR) rate but also resists thermal aggregation and carbon deposition. The Ni@STFN/GDCN cathode operating in pure CO 2 with an applied voltage of 1.6 V achieves a current density of 1.85 A cm−2, surpassing most of the advanced electrodes reports by other works. Furthermore, the CO 2 RR testing at a current density of 1.5 A cm−2 shows no significant voltage fluctuations during 180 h, demonstrating excellent long-term stability. Our testing results show that the in-situ dual-exsolved nanometal anchoring on heterogeneous composite nanofiber is a reliable and stable SOEC cathode for direct and highly efficient CO 2 electrolysis. [Display omitted] • Highly active and robust STFN/GDCN heterogeneous nanofiber cathode. • Nanofibers with exsolved nanometal boost electrolysis performance. • The excellent electrolysis activity of 1.85 A cm−2 is achieved at 1.6V. • Ni@STFN/GDCN exhibits remarkable electrolysis stability over 180 h. [ABSTRACT FROM AUTHOR]

Exsolution, as an effective approach to constructing particle-decorated interfaces, is still challenging to yield interfacial films rather than isolated particles. Inspired by in vivo near-infrared laser photothermal therapy, using 3 mol% Y _2 O _3 stabilized tetragonal zirconia polycrystals (3Y-TZP) as host oxide matrix and iron-oxide (Fe _3 O _4 / γ -Fe _2 O _3 / α -Fe _2 O _3 ) materials as photothermal modulator and exsolution resource, femtosecond laser ultrafast exsolution approach is presented enabling to conquer this challenge. The key is to trigger photothermal annealing behavior via femtosecond laser ablation to initialize phase transition from monoclinic zirconia (m-ZrO _2 ) to tetragonal zirconia (t-ZrO _2 ) and induce t-ZrO _2 columnar crystal growth. Fe-ions rapidly segregate along grain boundaries and diffuse towards the outmost surface, and become ‘frozen’, highlighting the potential to use photothermal materials and ultrafast heating/quenching behaviors of femtosecond laser ablation for interfacial exsolution. Triggering interfacial iron-oxide coloring exsolution is composition and concentration dependent. Photothermal materials themselves and corresponding photothermal transition capacity play a crucial role, initializing at 2 wt%, 3 wt%, and 5 wt% for Fe _3 O _4 / γ -Fe _2 O _3 / α -Fe _2 O _3 doped 3Y-TZP samples. Due to different photothermal effects, exsolution states of ablated 5 wt% Fe _3 O _4 / γ -Fe _2 O _3 / α -Fe _2 O _3 -doped 3Y-TZP samples are totally different, with whole coverage, exhaustion (ablated away) and partial exsolution (rich in the grain boundaries in subsurface), respectively. Femtosecond laser ultrafast photothermal exsolution is uniquely featured by up to now the deepest microscale (10 μ m from 5 wt%-Fe _3 O _4 -3Y-TZP sample) Fe-elemental deficient layer for exsolution and the whole coverage of exsolved materials rather than the formation of isolated exsolved particles by other methods. It is believed that this novel exsolution method may pave a good way to modulate interfacial properties for extensive applications in the fields of biology, optics/photonics, energy, catalysis, environment, etc.

Electrochemical reduction of CO2 into valuable fuels and chemicals has become a contemporary research area, where the heterogeneous catalyst plays a critical role. Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation. Here, we review the CO2 reduction with active materials prepared by exsolution. The fundamental of exsolution was summarized in terms of mechanism and models, materials, and driven forces. The advances in the exsolved materials used in high-temperature CO2 electrolysis were catalogued into tailored interfaces, synergistic effects on alloy particles, phase transition, reversibility and electrochemical switching.

Introduction: Innovating technologies to efficiently reduce carbon dioxide (CO2) emission or covert it into useful products has never been more crucial in light of the urgent need to transition to a net-zero economy by 2050. The design of efficient catalysts that can make the above a viable solution is of essence. Many noble metal catalysts already display high activity, but are usually expensive. Thus, alternative methods for their production are necessary to ensure more efficient use of noble metals.Methods: Exsolution has been shown to be an approach to produce strained nanoparticles, stable against agglomeration while displaying enhanced activity. Here we explore the effect of a low level of substitution of Ni into a Rh based A-site deficienttitanate aiming to investigate the formation of more efficient, low loading noblemetal catalysts.Results: We find that with the addition of Ni in a Rh based titanate exsolution is increased by up to ∼4 times in terms of particle population which in turn results in up to 50% increase in its catalytic activity for CO2 conversion.Discussion: We show that this design principle not only fulfills a major research need in the conversion of CO2 but also provides a step-change advancement in the design and synthesis of tandem catalysts by the formation of distinct catalytically active sites.

We have developed a general route for combining Ni, Fe, Co, Cu, and Pd in a nanoparticle using the exsolution mechanism from LaFe0.7Ni0.1Co0.1Cu0.05Pd0.05O3 perovskite oxide precursors. The strong adherence of the nanoparticles to the support yields attractive catalytic properties for dry methane reforming, such as coke resistance and thermal sintering suppression. The reduction of the precursors at 700 and 900 °C yielded NiCoCuPd or NiFeCoCuPd nanoparticles with a size-dependent phase transition from a complex concentrated alloy to phase-separated heterostructures. Our findings indicate that smaller concentrated alloy nanoparticles (∼10 nm) are more effective for methane activation than larger (>20 nm) phase-separated nanoparticles. [ABSTRACT FROM AUTHOR]

Spinodal decomposition is an important mechanism of exsolution. However, spinodal decomposition has not been observed in natural sulfide intergrowths. We utilized focused ion beam (FIB) and transmission electron microscopy (TEM) techniques to confirm spinodal decomposition in natural sulfide intergrowths (chalcopyrite and bornite). According to FIB and TEM analyses, spinodal decomposition occurred as small and curving alternating dark and bright fluctuations in natural bornite–chalcopyrite intergrowths. Due to the low temperature that drove the exsolution mechanism, fluctuations ~10 nm wide and 20–200 nm long contained non-stoichiometric and tetragonal bornite and chalcopyrite. The corresponding electron diffraction of spinodal decomposition displayed a satellite spot in the [−210] direction for bornite, and the (200)* and (224)* of chalcopyrite paralleled the (24−2)* and (242)* of bornite, respectively. These observations all agreed with spinodal decomposition, two coexisting phases formed with a crystallographic orientation relationship, which indicated the first observation of spinodal decomposition in natural sulfide intergrowths. These findings confirmed that spinodal decomposition is a mechanism for natural crystal growth. As spinodal decomposition is larger in extent and faster than nucleation and growth, other Cu ore deposits may also form via this mechanism. [ABSTRACT FROM AUTHOR]

Hydrogen production through the bi-reforming of methane over exsolution-derived Ni catalysts has been studied. Nickel-based catalysts were prepared through the activation of (CeM)1−xNixOy (M = Al, La, Mg) solid solutions in a reducing gaseous medium. Their performance and resistance to coking under the reaction conditions were controlled by regulating their textural, structural, morphological, and redox properties through adjustments to the composition of the oxide matrix (M/Ce = 0–4; x = 0.2–0.8; y = 1.0–2.0). The role of the M-dopant type in the genesis and properties of the catalysts was established. The efficiency of the catalysts in the bi-reforming of methane increased in the following series of M: M-free < La < Al < Mg, correlating with the structural behavior of the nickel active component and the anti-coking properties of the support matrix. The preferred M-type and M/Ce ratio determined the best performance of (CeM)1−xNixOy catalysts. At 800 °C the optimum Ce0.6Mg0.2Ni0.2O1.6 catalyst provided a stable H2 yield of 90% at a high level of CO2 and CH4 conversions (>85%). [ABSTRACT FROM AUTHOR]

High‐performance nanoparticle platforms can drive catalysis progress to new horizons, delivering environmental and energy targets. Nanoparticle exsolution offers unprecedented opportunities that are limited by current demanding process conditions. Unraveling new exsolution pathways, particularly at low‐temperatures, represents an important milestone that will enable improved sustainable synthetic route, more control of catalysis microstructure as well as new application opportunities. Herein it is demonstrated that plasma direct exsolution at room temperature represents just such a step change in the synthesis. Moreover, the factors that most affect the exsolution process are identified. It is shown that the surface defects produced initiate exsolution under a brief ion bombardment of an argon low‐pressure and low‐temperature plasma. This results in controlled nanoparticles with diameters ≈19–22 nm with very high number densities thus creating a highly active catalytic material for CO oxidation which rivals traditionally created exsolved samples. [ABSTRACT FROM AUTHOR]

Six different perovskite-type oxides were investigated with respect to their ability for methanol synthesis via H2 and CO2: Fe-, Mn-, and Ti-based perovskites were prepared with and without Cu doping. For assessment, the catalysts were subjected to preliminary tests at atmospheric pressure to evaluate their ability to activate CO2. Additional catalytic tests with the doped versions of each catalyst type were carried out in a pressured reactor at 21 bar. After the measurements, the catalysts were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). All catalysts were able to produce methanol in the pressure tests. CO2 conversions between 14% and 23% were reached at 400 °C, with the highest methanol selectivity at the lower temperature of 250 °C. The combination of XRD and SEM revealed that the Fe-based and Ti-based perovskites were stable under reaction conditions and that catalytically highly active and stable nanoparticles had formed. The minor formation of CaCO3, which is a deactivating phase, was observed for one catalyst. These nanoparticles showed resistance to coking and sintering. However, the yield and selectivity for methanol need to be improved via the further tailoring of the perovskite composition. [ABSTRACT FROM AUTHOR]

Copper-based catalysts are the choice for producing multi-carbon products (C 2+ ) during CO 2 electroreduction (CO 2 RR), where the Cu 0 Cu δ+ pair sites are proposed to be synergistic hotspots for C-C coupling. Maintaining their dynamic stability requires precise control over electron affinity and anion vacancy formation energy, posing significant challenges. Here, we present an in situ reconstruction strategy to create dynamically stable Cu 0 Cu 0.18+ OCa motifs at the interface of exsolved Cu nanoclusters and CaCO 3 nanospheres (Cu/CaCO 3 ). In situ XAFS analysis confirmed the low-valency state of Cu δ+ during CO 2 RR. DFT calculations demonstrated that the nanocluster size arises from the balance between metal-support interactions and Cu-Cu cohesive energy, while the dynamic stability of rich interfacial Cu δ+ sites is attributed to their low electron affinity and high CO 3 2- vacancy formation energy, which collectively contribute to reduced reducibility. The transformed Cu/CaCO 3 exhibits an impressive C 2+ Faradaic efficiency of 83.7 % at a partial current density of 393 mA cm -2 , facilitated by adsorption of *CO with varying electronegativity at heterogeneous copper sites that lowers the C-C coupling energy barrier. Our findings establish insoluble carbonate as an effective anion pairing for Cu 0 Cu δ+ sites, highlighting the effectiveness of the in situ reconstitution strategy in producing a high density of dynamically stable Cu 0 Cu δ+ pair sites., (© 2025 Wiley-VCH GmbH.)

Double perovskite (DP) oxides are promising electrode materials for symmetric solid oxide cells (SSOCs) due to their excellent electrochemical activity and stability. B-site cation doping in DP oxides affects the reversibility of phase transformation and exsolution, which plays a crucial role in the catalyst recovery. Yet, few studies have been conducted on this topic. In this study, the Sr 2 Fe 1.5-x Co x Mo 0.5 O 6-δ (CSFM, x = 0, 0.1, 0.3, 0.5) DP system demonstrates modulated exsolution and phase transformation reversibility by manipulating the oxygen vacancy concentration. The correlation between Co-doping level and oxygen vacancy concentration is investigated to optimize the exsolution and phase transformation properties. Sr 2 Fe 1.2 Co 0.3 Mo 0.5 O 6-δ (3CSFM) exhibits reversible transformation between DP and Ruddlesden-Popper phases with a high density of exsolved CoFe nanoparticles under redox atmospheres. The quasi-symmetric cell with 3CSFM shows a peak power density of 1.27 W cm -2 at 850 °C in H 2 fuel cell mode and a current density of 2.33 A cm -2 at 1.6 V and 800 °C in H 2 O electrolysis mode. The 3CSFM electrode exhibits robust stability during continuous operation for ≈700 h. These results demonstrate the significant role of B-site doping in designing DP materials capable of dynamic phase transformation in diverse environments., (© 2024 Wiley‐VCH GmbH.)

In order to clarify the role of R2O3 in the metal-oxide catalysts derived from complex oxide precursors, a series of R1.5Ca0.5NiO4 (R = Nd, Sm, Eu) complex oxides was obtained. A significant systematic increase in the orthorhombic distortion of the R1.5Ca0.5NiO4 structure (K2NiF4 type, Cmce) from Nd to Eu correlates with a corresponding decrease in their ionic radii. A reduction of R1.5Ca0.5NiO4 in the Ar/H2 gas mixture at 800 °C causes a formation of dense agglomerates of CaO and R2O3 coated with spherical 25–30 nm particles of Ni metal. The size of metal particles and oxide agglomerates is similar in all Ni/(R2O3,CaO) composites in the study. Their morphology is rather similar to the products of redox exsolution obtained by the partial reduction of complex oxides. All obtained composites demonstrated a significant catalytic activity in the dry reforming (DRM) and partial oxidation (POM) of methane at 700–800 °C. A systematic decrease in the DRM catalytic activity of composites from Nd to Eu could be attributed to the basicity reduction of R2O3 components of the composite catalysts. The maximum CH4 conversion in POM reaction was observed for Ni/(Sm2O3,CaO), while the maximum selectivity was demonstrated by Nd2O3-based composite. The possible reasons for the observed difference are discussed. [ABSTRACT FROM AUTHOR]

To design metal nanoparticles (NPs) on a perovskite surface, the exsolution method has been extensively used for efficient catalytic reactions. However, there are still the challenges of finding a combination and optimization for the NPs' control. Thus, we report in situ control of the exsolved Ni NPs from perovskite to apply as a catalyst for dry reforming of methane (DRM). The La0.8Ce0.1Ti0.6Ni0.4O3 (LCTN) is designed by Ce doping to incorporate high amounts of Ni in the perovskite lattice and also facilitate the exsolution phenomenon. By control of the eluted Ni NPs through exsolution, the morphological properties of exsolved Ni NPs are observed to have a size range of 10~49 nm, while the reduction temperatures are changed. At the same time, the chemical structure of the eluted Ni NPs is also changed by an increased reduction temperature to a highly metallic Ni phase with an increased oxygen vacancy at the perovskite oxide surface. The optimized composite nanomaterial displays outstanding catalytic performance of 85.5% CH4 conversion to produce H2 with a value of 15.5 × 1011 mol/s·gcat at 60.2% CO conversion, which shows the importance of the control of the exsolution mechanism for catalytic applications. [ABSTRACT FROM AUTHOR]

Relative alignments of mineral exsolutions and their host crystals can be described by crystallographic orientation relationships (COR). Exsolved phases in garnet from high‐grade metamorphic rocks and igneous rocks may have COR, but the complexity of COR distributions has thus far restricted their use to identifying exsolved phases. Classification of COR also remains mineral‐specific, leaving doubt as to what information COR preserve. To test how COR may be standardized, we calculated mismatch of low‐index crystallographic planes (d‐value ratios) and crystallographic directions (rows of atoms) between precipitates and garnet and defined search criteria for structural alignments likely to be energetically favourable. We analysed published electron backscatter diffraction (EBSD) data for apatite, rutile, ilmenite, corundum, and quartz precipitates in garnet (ntot = 1,296) for the presence of these alignments. Our method predicts between 88% and 98% of observed alignments across the studied minerals and requires only calculations using unit cell parameters. We further show that each exsolved mineral forms COR predicted by the edge‐to‐edge matching model which was developed to describe unambiguous exsolution textures in alloys. Edge‐to‐edge matching aligns atoms at the host–precipitate interface by parallelism or near‐parallelism of crystallographic planes of similar spacing and parallelism of crystallographic directions (rows of atoms) of similar length on the edges of those planes. Edge‐to‐edge matches likely facilitate coherent to semi‐coherent interfaces by lowering surface free energy and strain energy, stabilizing precipitates. These matches are defined by criteria applicable to all minerals, making them an ideal tool for classifying, discovering and interpreting COR of diverse precipitates in garnet. This approach may also predict COR in other geological mineral pairs (e.g., exsolved feldspars). We find that edge‐to‐edge matching may explain the stability of the needle‐shaped morphologies commonly observed for exsolution textures in garnet. Edge‐to‐edge matching COR distributions can be tested as proxies of the state of the host rock at the time of exsolution to evaluate factors such as temperature, cooling rate, degree of undercooling, and/or strain. Patterns of edge‐to‐edge matching COR may be paired with geothermobarometry and/or petrochronology to provide a powerful new tool for studying the histories of granulite and eclogite facies metamorphic and igneous rocks. [ABSTRACT FROM AUTHOR]

Active and durable catalytic material for ammonia (NH 3) decomposition reaction is attracting attentions for utilization of NH 3 as an innovative hydrogen carrier. In this study, diverse single metal and alloy nano catalysts are prepared via in-situ exsolution method and their NH 3 decomposition properties are evaluated. Transition metal cations (Ni, Co, Fe ions) are doped into the La 0.43 Ca 0.37 M x N y Ti 1-(x+y) O 3-δ (LCMNT) perovskite oxide structure and exsolved on its surface as supported nano particles under reduction condition. The maximum doping level and chemical composition of exsolution catalysts are investigated to optimize their NH 3 decomposition activity. The exsolution catalyst demonstrates improved NH 3 decomposition characteristics compared to conventionally prepared infiltration catalysts, indicating higher conversion efficiency and H 2 production rate. The exsolved nano catalysts also exhibit great thermochemical stability against catalyst agglomeration or surface nitriding. The results obtained in this study suggest the potential utilization of exsolution catalysts for on-site production of H 2 through NH 3 decomposition catalysis. [Display omitted] • Single and alloy nano exsolution catalysts are prepared on a perovskite oxide with optimized Ni, Co, and Fe doping level. • The exsolution catalysts exhibited much higher NH 3 conversion ratio compared to Ni infiltration catalyst. • Co exsolution catalyst showed the highest NH 3 conversion ratio and H 2 production rate than other exsolution catalysts. [ABSTRACT FROM AUTHOR]

The practical applications of SnO 2 materials for NO 2 detection in the field of indoor air quality monitoring are strongly plagued by low sensitivity toward ppb-level NO 2. Herein, an in situ exsolution strategy was developed to prepare Sn-containing materials with abundant oxygen vacancy defects and Sn/SnO 2 heterojunctions (designated as Sn/SnO 2-x), which were obtained by annealing mixture of commercial SnO 2 and NaBH 4 in Ar atmosphere. Compared to commercial SnO 2 , the optimal Sn/SnO 2-x -3 displays the obvious advantages of low operating temperature (110 °C), high sensitivity (response value of 4.65 toward 80 ppb NO 2), and low limit of detection (10 ppb NO 2 with response value of 1.17). The improvement of NO 2 sensing performances is attributed to the synergistic effect of introducing oxygen vacancy defects and constructing Sn/SnO 2 heterojunctions. Theoretically, the former leads to increasing the active sites for adsorption of NO 2 and the latter reduces the band gap for improvement of carrier concentration. Additionally, this NO 2 sensor shows excellent sensing performances for monitoring NO 2 concentration in simulated indoor environment. This work not only provides an effective and large-scale approach to prepare novel sensing materials from commercial metal oxides by exsolution method, but also opens the way to fabricate high-performance gas sensors for detection of NO 2 with low concentrations. • An exsolution strategy was developed to prepare Sn/SnO 2-x with abundant oxygen vacancies and Sn/SnO 2 heterojunctions. • Sn/SnO 2-x exhibits high response value of 4.65 toward 80 ppb NO 2 at 100 °C and low limit of detection of 10 ppb. • This work opens the way for fabrication of high-performance gas sensors for detection of NO 2 with low concentrations. [ABSTRACT FROM AUTHOR]

Because the 6p orbital of Bi is easily combined with the 2p orbital of N, doping Bi can effectively inhibit HER and boost NRR. [Display omitted] • A high-performance NRR electrocatalyst La 0.9 Bi 0.1 FeO 3-δ was developed. • The electron reconstruction of the catalyst surface facilitates the electron transfer. • A new electron transfer chain Bi3+/Bi2+/Bi0 was created. • The electrocatalytic machnism for inhibit HER and improve eNRR was explored. The electrochemical nitrogen reduction reaction (eNRR) displays significant potential for the synthesis of ammonia. However, eNRR electrocatalysts with high catalytic activity and selectivity still need to be developed. In this study, a Bi-doped La 0.9 Bi 0.1 FeO 3-δ (LBiF) perovskite was fabricated as a potential cathode catalyst and incorporated into a protonic ceramic electrolysis cell (PCEC) for eNRR. Electrochemical tests demonstrated that the LBiF cathode reveals higher eNRR catalytic activity and enhanced hydrogen evolution reaction (HER) inhibition compared to undoped LaFeO 3 (LF). Characterization of the LBiF cathode following 90 h of NH 3 synthesis revealed surface reconstruction of the catalyst during eNRR. Particularly, Bi3+ is partially reduced to Bi2+ and metallic Bi, resulting in A-site defects and an increased concentration of oxygen vacancies (OVs) and Fe4+ in accordance with the charge neutrality principle. Both the OVs and Fe4+ can accept electron pairs provided by N 2 due to their unsaturated electronic structures. Furthermore, Bi doping inhibits the HER because Bi preferentially binds to N instead of H. Bi doping creates new Bi3+/Bi2+/Bi0 redox electron pairs, establishing an electron transfer path that improves perovskite conductivity and eNRR electrocatalytic activity. This study sets a foundation for designing eNRR catalysts aimed at suppressing the HER. [ABSTRACT FROM AUTHOR]

[Display omitted] • The biphasic interface formed by Mn 0.1 CFO catalyst has excellent interfacial effect. • The composition of the active component of the catalyst can be effectively adjusted. • Continuous exsolution of the active component can prolong the life of the catalyst. • Monolithic catalyst realizes long-term degradation of simulated wastewater. • Radicals and non-radicals act synergistically. The development of catalysts with fast reaction rates and long service life remains a significant challenge in advanced oxidation processes. The research applied the property that Mn could occupy both tetrahedral and octahedral sites in the spinel structure. By adjusting Mn composition engineering in CuFe 2 O 4 , it could regulate the proportion of active components in spinel constituents and form the hybrid catalyst of Mn-doped CuFe 2 O 4 /CuO. CuFe 2 O 4 /CuO biphasic interface caused lattice distortion, effectively enhancing the interface interaction, which was conducive to the gradual exsolution and redeposition of the active component CuFe 2 O 4 during the catalytic reaction process, thereby prolonging the service life of the catalyst. Within 30 min, the removal rate of tetracycline hydrochloride was 97.3%, while peroxymonosulfate (PMS) stoichiometric efficiency was 0.12. The degradation effect of the powder catalyst only decreased by 7.3% after 6 cycles. In the self-made fixed bed, the mass ratio of sodium alginate solidified catalyst to sewage treatment capacity could reach 1:33000. These results indicated that Mn doping could effectively improve the catalytic degradation performance of CuFe 2 O 4 and prolong the service life of the catalyst by forming a two-phase interface. Furthermore, sodium alginate curing catalysts could provide new insights into the industrial application of catalysts. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) has been emerging as a viable solution to achieving carbon neutrality enhanced by the Paris Agreement as it converts the greenhouse gases of CO2 and CH4 into industrially useful syngas. However, there have been limited studies on the DRM catalyst under mild operating conditions with a high dilution gas ratio due to their deactivation from carbon coking and metal sintering. Herein, we apply the triple‐phase boundary (TPB) concept to DRM catalyst via exsolution phenomenon that can secure elongated TPB by controlling the Fe‐doping ratio in perovskite oxide. Remarkably, the exsolved catalyst with prolongated TPB shows exceptional CO2 and CH4 conversion rates of 95.9 % and 91.6 %, respectively, stable for 1000 hours under a dilution‐free system. DFT calculations confirm that the Lewis acid of support and Lewis base of metal at the TPB promote the adsorption of reactants, resulting in lowering the overall CO2 dissociation and CH4 dehydrogenation energy. [ABSTRACT FROM AUTHOR]

In diesel reforming, a catalyst is easily deteriorated by thermal sintering and coke formation. A proper preparation method improves stability by modifying the physicochemical properties of the catalyst. In this paper, the effects of preparation methods on exsolution and alloy formation in PtRu bimetallic catalysts for diesel reforming were studied. The catalysts were prepared by impregnation and combustion synthesis. The structure, surface morphology, and reduction characteristics of each catalyst were characterized by XRD, STEM, and H 2 -TPR. Based on these characterizations, the behavior of each catalyst in the reforming environment was identified by comparison of properties observed before and after the reaction. Pt and Ru individually crystallized from the impregnated catalyst, whereas Pt and Ru exsolved from the combustion synthesis catalyst to form a PtRu alloy. As a result, the combustion synthesis catalyst showed higher stability and coke resistance than the impregnated catalyst. [Display omitted] • PtRu bimetallic catalysts for diesel reforming were prepared by different methods. • In the impregnated catalyst, metals crystallized separately without forming alloys. • In the combustion synthesis catalyst, metals exsolved and formed alloy nanoparticles. • The PtRu alloy catalyst showed higher stability and coke resistance. [ABSTRACT FROM AUTHOR]

The present study reports the occurrence of orthopyroxene megacrysts from the Chilka Lake anorthosite massif, Eastern Ghats, India. An insight into the mineral chemistry of different phases, coupled with detailed field and petrographic evidences from this study, shed light on a long debate on the origin of orthopyroxene megacrysts in anorthosite massifs. The megacrysts contain exsolved lamellae of plagioclase and opaque oxides (ilmenite, rutile) oriented along orthopyroxene cleavage planes. The trace element distribution patterns of the megacryst and matrix plagioclase are mirror reflections of each other and mutually complementary. The calculated compositions of melts in equilibrium with these two phases show comparable patterns for LREE (light rare earth elements, La–Sm), but differ markedly in terms of HREE (heavy rare earth elements, Eu–Lu), suggesting that the megacrysts and matrix plagioclases did not crystallize simultaneously. We infer that the orthopyroxene megacrysts have a longer crystallization history, initially as a low-Ca non-quad member of the pyroxene group at pressure ≥ 10 kbar, incorporating some amount of Ca, Al and Ti in their structure. Subsequently, they have been carried by a plagioclase crystal mush to mid-crustal levels at pressure ~ 4–6 kbar following a near-isothermal decompression that may be linked to the emplacement of the anorthosite massif, giving rise to the exsolution lamellae of plagioclase and opaque oxides. [ABSTRACT FROM AUTHOR]

Perovskite materials with exsolved nanoparticles have a wide range of applications in energy conversion systems owing to their unique basal plane active sites and excellent catalytic properties. The introduction of A-site deficiency can help the formation of highly mobile oxygen vacancies and remarkably enhance the reducibility of Ni nanoparticles, thus significantly increasing electronic conductivity and catalytic activity simultaneously. Herein, we adopt pulsed electric current (PEC) treatment, a novel approach instead of the long-time high-temperature reduction technique, and for the first time review that the exsolution of minuscule Ni nanoparticles (8â€"20 nm) could be facilitated on Ni-doped La0.52Sr0.28Ti0.94Ni0.06O3 (LSTN) anodes with A-site deficiency. Encouragingly, finding that low PEC can successfully lead to nanoparticle exsolution and show a significantly improved oxygen evolution reaction performance of LSTN-PEC (LSTN after PEC treatment) possessing A-site deficiency, the onset potential of LSTN-PEC (500 V) (LSTN after PEC treatment with 500 Vâ€"4 Hzâ€"90 s) was advanced by 0.173 V, the R ct value was reduced by 82.38 Ω·cm2, and the overpotential was also reduced by 73 mV. [ABSTRACT FROM AUTHOR]

A garnet clinopyroxenite from the island of Fjørtoft, Western Gneiss Region (WGR) in Norway, has experienced a complex metamorphic evolution demonstrated by studies involving petrographic observations, mineral chemistry, phase equilibria modelling and geothermobarometry. This rock, originally an eclogite, documents ultrahigh‐pressure (UHP) conditions higher than 3.5 GPa (Stage 1), witnessed by Ca‐rich garnet inclusions in kyanite. The UHP assemblage was pervasively re‐equilibrated at high‐pressure (HP) granulite facies conditions around 1.75 GPa and 870°C, during which and/or somewhat before Ca‐poor garnet, sodian diopside, zoisite and biotite formed (Stage 2a). Dehydration melting of zoisite and biotite (Stage 2b) took place at similar pressure–temperature conditions. The produced melt was poor in Si and rich in alkalis and crystallized mainly to analcime + plagioclase + K‐feldspar. Oriented composite inclusions of quartz + amphibole + phengite ± garnet, found in clinopyroxene, are interpreted to have resulted from interaction between a fluid (hydrous melt and/or aqueous fluid) and clinopyroxene at the early retrogression Stage 3. Stage 1 resulted from deep subduction of the rock. Stage 2 followed after early exhumation probably due to stagnation at a hot and thickened orogenic root. Consequently, other HP granulite facies metabasites, which are similar to the studied garnet clinopyroxenite and widespread in the northwestern WGR, could have been transformed from former eclogite at this stage, too. In addition, this study provides a direct link between the generation of peralkaline melts and crustal anatexis in collision zones and new insights into the retrograde formation of oriented mineral inclusions in HP‐UHP minerals. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell (SOFC) is a mature opportunity for producing power energy in remote areas like islands, where access to the electrical grid is not favoured, and gas distribution is the only viable approach. In this context, generally, biogas represents the most convenient fuel resources in these areas. However, the direct use of biogas in SOFCs is still an issue to be solved due to its negative effect on the conventional Ni-YSZ anode. In this study, to overcome this issue, we suggested using a protective layer coated on the anode of a commercial SOFC. A nickel manganite showing mixed ionic and electronic conductivity tailored specifically for this approach was investigated. The preliminary characterisations showed that the formation of a Ruddlesden-Popper (RP) n = 1 structure supporting fine encapsulated particles based on Ni was formed around 800 °C in consequence of the reducing environment. The electrochemical experiments carried out for 270 h demonstrated for the coated cell significant stability in the presence of dry biogas, albeit an ageing effect was noticed in the electrical percolation of both cell electrodes. The post mortem analyses revealed an attractive redox property for the nickel manganite, which partially returned to the RP n = 2 phase. Moreover, the absence of carbon deposits on the anode suggests possible applications for this approach. • A Ruddlesden-Popper phase supported fine encapsulated particles of Ni. • A coated SOFC showed stable behaviour in dry-biogas. • Power generation required multiple redox reactions. [ABSTRACT FROM AUTHOR]

Exsolution of metallic nanoparticles (NPs) from oxide supports offers a novel approach to design high-performance materials in the field of heterogeneous catalysis and energy conversion and storage. Here, we report the homogenous exsolution of Pd NP s with an average size of 100 nm in compressive strained La 0.6 Sr 0.4 Fe 0.9 Pd 0.1 O 3-δ (LSFPd) thin films. We systematically explored the electrical resistivity and the redox stability of LSFPd thin films upon exsolution of NP s. Compared to La 0.6 Sr 0.4 FeO 3-δ (LSF) thin films, whose electrical response was controlled by oxygen stoichiometry, LSFPd films showed a more stable electrical response in redox cycling with similar resistivity values both in air and hydrogen. The improved stability was attributed to dynamic and exsolution of NP s. Our study showed that the control of exsolution of NP s can provide a new way to regulate the electrical response of perovskite oxide semiconductors under external stimuli (i.e., atmosphere), which could be beneficial for the rational design of high-performance functional materials for micro solid oxide fuel cells, nano-sensors, and nano-actuators applications. In addition to increased oxygen vacancies emerging from LSF crystal lattice after the reduction treatment, Pd ions doped in the B-site of perovskite could be reduced and exsolved as NPs on the surface of LSFPd films, leading to the improved stability of electrical response. [Display omitted] [ABSTRACT FROM AUTHOR]

Decorating metallic nanoparticles on the surface of oxide support is a promising approach to tailor the catalytic activity of perovskite. Here, for the first time using thermal shock to rapidly fabricate nanoparticle‐decorated materials (NDMs) is proposed. Low‐cost and size‐tailorable carbon paper is used as the heating source during the thermal shock. It is reported that by thermal shock technique, only ≈13 s including heating and treating time is needed to fabricate the exsolution‐based NDMs (the fastest method to date). Benefitted by the sufficiently provided driving force and the short treating time, as compared to the product prepared by the conventionally furnace‐based method, higher particle density and smaller particle size of the exsolved catalysts are acquired for the thermal shock fabricated NDM, giving rise to a fascinating improvement (12‐fold) of the electrochemical performance. This work develops a new technique to rapidly fabricate NDMs in an economic and high‐throughput manner, profoundly improving the flexibility of the application of exsolution‐based materials in electrochemical devices. [ABSTRACT FROM AUTHOR]

The extensive emission of CO2 results in critical environmental issues, such as global warming. Photocatalytic CO2 conversion is a meaningful route to convert CO2 into useful chemicals. However, the highly selective reduction of CO2 with the avoidance of hydrogen evolution is still challenging. Herein, the photocatalytic reduction CO2 to synthesis gas (syngas) was achieved on a metal Ag socketed perovskite LaFeO3 (LFO) catalytic interface prepared by an in‐situ exsolution method. The conduction band of Ag‐exsolved LFO is more negative than LFO, benefiting efficient CO2 reduction. By tuning the dopant Ag cation in the lattice to nanoparticles pinned on the surface, the CO formation rate was improved around five‐fold from 0.51 to 2.41 μmol g−1 h−1. Meanwhile, the H2/CO molar ratio also showed strong dependence on the modality of Ag at the metal‐perovskite interface. The design offers a promising pathway for transforming CO2 to valuable chemicals based on efficient photocatalysts design. [ABSTRACT FROM AUTHOR]

Nanoparticle exsolution has emerged as a versatile method to functionalize oxides with robust metallic nanoparticles for catalytic and energy applications. By modifying certain external parameters during thermal reduction (temperature, time, reducing gas), some morphological and/or compositional properties of the exsolved nanoparticles can be tuned. Here, it is shown how the application of high pressure (<100 bar H 2 ) enables the control of the exsolution of ternary FeCoNi alloyed nanoparticles from a double perovskite. H 2 pressure affects the lattice expansion and the nanoparticle characteristics (size, population, and composition). The composition of the alloyed nanoparticles could be controlled, showing a reversal of the expected thermodynamic trend at 10 and 50 bar, where Fe becomes the main component instead of Ni. In addition, pressure drastically lowers the exsolution temperature to 300 °C, resulting in unprecedented highly-dispersed and small-sized nanoparticles with a similar composition to those obtained at 600 °C and 10 bar. The mechanisms behind the effects of pressure on exsolution are discussed, involving kinetic, surface thermodynamics, and lattice-strain factors. A volcano-like trend of the exsolution extent suggests that competing pressure-dependent mechanisms govern the process. Pressure emerges as a new design tool for metallic nanoparticle exsolution enabling novel nanocatalysts and surface-functionalized materials., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Ammonia has emerged as a promising fuel for solid oxide fuel cells (SOFCs) owing to its high energy density, high hydrogen content, and carbon-free nature. Herein, the electrocatalytic potential of a novel Ni-doped SFM double-perovskite (Sr 1.9 Fe 0.4 Ni 0.1 Mo 0.5 O 6-δ ) is studied, for the first time, as an alternative anode material for symmetrical direct-ammonia SOFCs. Scanning and transmission electron microscopy characterization has revealed the exsolution of Ni-Fe nanoparticles (NPs) from the parent Sr 2 Fe 1.5 Mo 0.5 O 6 under anode conditions, and X-ray diffraction has identified the FeNi 3 phase after exposure to ammonia at 800 °C. The active-exsolved NPs contribute to achieving a maximal ammonia conversion rate of 97.9% within the cell's operating temperatures (550-800 °C). Utilizing 3D-printed symmetrical cells with SFNM-GDC electrodes, the study demonstrates comparable polarization resistances and peak power densities of 430 and 416 mW cm -2 for H 2 and NH 3 fuels, respectively, with long-term stability and a negligible voltage loss of 0.48% per 100 h during ammonia-fed extended galvanostatic operation. Finally, the ammonia consumption mechanism is elucidated as a multistep process involving ammonia decomposition, followed by hydrogen oxidation. This study provides a promising avenue for improving the performance and stability of ammonia-based SOFCs for potential applications in clean energy conversion technologies.

An advanced materials solution utilizing the concept of "smart catalysts" could be a game changer for today's automotive emission control technology, enabling the efficient use of precious metals via their two-way switching between metallic nanoparticle forms and ionic states in the host perovskite lattice as a result of the cyclical oxidizing/reducing atmospheres. However, direct evidence for such processes remains scarce; therefore, the underlying mechanism has been an unsettled debate. Here, we use advanced scanning transmission electron microscopy to reveal the atomic-scale behaviors for a LaFe 0.95 Pd 0.05 O 3 -supported Ir-Pd-Ru nanocatalyst under fluctuating redox conditions, thereby proving the reversible dissolution/exsolution for Ir and Ru but with a limited occurrence for Pd. Despite such selective dissolution during oxidation, all three elements remain cooperatively alloyed in the subsequent reduction, which is a key factor in preserving the catalytic activity of the ternary nanoalloy while displaying its self-regenerating functionality and control of particle agglomeration.

Nanostructured functional oxides play an important role in enabling clean energy technologies and novel memory and processor devices. Using thin‐film La0.6Sr0.4FeO3 (LSF) as a model system, the novel utility of exsolution in fabricating self‐assembled metal oxide nanocomposites with tunable functionalities is shown. Exsolution triggers the formation of metallic iron (Fe0) nanoparticles, Ruddlesden–Popper domains, and nm‐scale percolated Fe‐deficient channels in LSF. Combining multimodal characterization with numerical modeling, the chemical, magnetic, and electrical properties of the exsolution‐synthesized nanocomposite at different stages of Fe0 exsolution as well as during redox cycling are assessed. After exsolution, the electronic conductivity of the nanocomposite LSF increased by more than two orders of magnitude. Based on numerical analysis representing all the constituents, it is expected that this increase in conductivity originates mainly from the Fe‐deficient percolating channels formed during exsolution. Moreover, the exsolved nanocomposite is redox‐active even at moderate temperatures. Such redox capabilities can enable dynamic control of the nanocomposite functionality by tailoring the oxygen non‐stoichiometry. This concept is demonstrated with a continuous modulation of magnetization between 0 and 110 emu cm−3. These findings point out that exsolution may serve as a platform for scalable fabrication of complex metal oxide nanocomposites for electrochemical and electronic applications. [ABSTRACT FROM AUTHOR]

Dry reforming of CH4/CO2 provides an attractive route to convert greenhouse gas into syngas; however, the resistance to sintering and coking of catalyst remains a fundamental challenge at high operation temperatures. Here we create active and durable metal–oxide interfaces in porous single‐crystalline (PSC) CeO2 monoliths with in situ exsolved single‐crystalline (SC) Ni particles and show efficient dry reforming of CH4/CO2 at temperatures as low as 450 °C. We show the excellent and durable performance with ≈20 % of CH4 conversion and ≈30 % of CO2 conversion even in a continuous operation of 240 hours. The well‐defined active metal–oxide interfaces, created by exsolving SC Ni nanoparticles from PSC NixCe1−xO2 to anchor them on PSC CeO2 scaffolds, prevent nanoparticle sintering and enhance the coking resistance due to the stronger metal–support interactions. Our work would enable an industrially and economically viable path for carbon reclamation, and the technique of creating active and durable metal–oxide interfaces in PSC monoliths could lead to stable catalyst designs for many challenging reactions. [ABSTRACT FROM AUTHOR]

Perovskite oxides with dispersed nanoparticles on their surface are considered instrumental in energy conversion and catalytic processes. Redox exsolution is an alternative method to the conventional deposition techniques for directly growing well‐dispersed and anchored nanoarchitectures from the oxide support through thermochemical or electrochemical reduction. Herein, a new method for such nanoparticle nucleation through the exposure of the host perovskite to plasma is shown. The applicability of this new method is demonstrated by performing catalytic tests for CO2 hydrogenation over Ni exsolved nanoparticles prepared by either plasma or conventional H2 reduction. Compared to the conventional thermochemical H2 reduction, there are plasma conditions that lead to the exsolution of a more than ten times higher Ni amount from a lanthanum titanate perovskite, which is similar to the reported values of the electrochemical method. Unlike the electrochemical method, however, plasma does not require the integration of the material in an electrochemical cell, and is thus applicable to a wide range of microstructures and physical forms. Additionally, when N2 plasma is employed, the nitrogen species are stripping out oxygen from the perovskite lattice, generating a key chemical intermediate, such as NO, rendering this technology even more appealing. [ABSTRACT FROM AUTHOR]

Plagioclase hosted needle- and lath-shaped magnetite micro-inclusions from oceanic gabbro dredged at the mid-Atlantic ridge at 13° 01–02′ N, 44° 52′ W were investigated to constrain their formation pathway. Their genesis is discussed in the light of petrography, mineral chemistry, and new data from transmission electron microscopy (TEM). The magnetite micro-inclusions show systematic crystallographic and shape orientation relationships with the plagioclase host. Direct TEM observation and selected area electron diffraction (SAED) confirm that the systematic orientation relations are due to the alignment of important oxygen layers between the magnetite micro-inclusions and the plagioclase host, a hypothesis made earlier based on electron backscatter diffraction data. Precipitation from Fe-bearing plagioclase, which became supersaturated with respect to magnetite due to interaction with a reducing fluid, is inferred to be the most likely formation pathway. This process probably occurred without the supply of Fe from an external source but required the out-diffusion of oxygen from the plagioclase to facilitate partial reduction of the ferric iron originally contained in the plagioclase. The magnetite micro-inclusions contain oriented lamellae of ilmenite, the abundance, shape and size of which indicate high-temperature exsolution from Ti-rich magnetite constraining the precipitation of the magnetite micro-inclusions to temperatures in excess of ~ 600 °C. This is above the Curie temperature of magnetite, and the magnetic signature of the magnetite-bearing plagioclase grains must, therefore, be considered as the thermoremanent magnetization. [ABSTRACT FROM AUTHOR]

Over the last decade, exsolution has emerged as a powerful new method for decorating oxide supports with uniformly dispersed nanoparticles for energy and catalytic applications. Due to their exceptional anchorage, resilience to various degradation mechanisms, as well as numerous ways in which they can be produced, transformed and applied, exsolved nanoparticles have set new standards for nanoparticles in terms of activity, durability and functionality. In conjunction with multifunctional supports such as perovskite oxides, exsolution becomes a powerful platform for the design of advanced energy materials. In the following sections, we review the current status of the exsolution approach, seeking to facilitate transfer of ideas between different fields of application. We also explore future directions of research, particularly noting the multi-scale development required to take the concept forward, from fundamentals through operando studies to pilot scale demonstrations.

Peridotites in ophiolites exposed along Himalayan suture zone open window to study deep Earth processes. We report c.2 km thick well exposed mantle section of Shergol ophiolite in the Indus Suture Zone (ISZ). The mantle section comprises lherzolite, serpentinised peridotite with cumulate chromitites. The in situ evidences from micron-sized mineral exsolutions are studied using optical microscopy, scanning electron microscopy and micro-Raman spectroscopy. From the ISZ lherzolite, ilmenite mineral exsolution is noted in the olivine grain. The exsolved ilmenites are oriented topotactically following former {111} planes of magnetite, providing evidence of spinel precursor. In another observation, the disoriented 1–3 µm wide and 10–80 µm long ilmenite needles are hosted in the olivine, is characterised by Raman peaks at 685, 370 cm−1 with low peaks at 308 cm−1,523 cm−1, 683 cm−1, 693 cm−1 and 731 cm−1 point to mixed mineral phases of magnetite with Cr–Fe–Al. Based on morphologies, crystal-chemical structure and modal calculation of exsolutions, we infer, exsolved Fe–Ti phases in Shergol peridotite is sourced from deeper part of the upper mantle. With the Fe–Ti phases, tiny silicate inclusions in chrome spinel and accompanying opaque base metal sulphides are also observed in the same peridotite, attributes successive stages of partial melting and subsequent cooling of metal enriched mantle. These observations, challenge shallow intra-oceanic arc setting for Shergol ophiolite and proposes, part of exsolved mineral phases in ophiolite has deep Earth origin. These mineral phases would ascent at the shallow mantle level beneath Neotethyan spreading ridge aided by dunite channel. [ABSTRACT FROM AUTHOR]

A temperature‐controlled cation‐exchange approach is introduced to achieve a unique dual‐exsolution in perovskite La0.8Fe0.9Co0.1O3−δ where both CoFe alloy and Co metal are simultaneously exsolved from the parent perovskite, forming an alloy and metal co‐decorated perovskite oxide. Mossbauer spectra show that cation exchange of Fe atoms in CoFe alloy and Co cations in the perovskite is the key to the co‐existence of Co metal and CoFe alloy. The obtained composite exhibits an enhanced catalytic activity as Li‐O2 battery cathode catalysts with a specific discharge capacity of 6549.7 mAh g−1 and a cycling performance of 215 cycles without noticeable degradation. Calculations show that the combination of decorated CoFe alloy and Co metal synergistically modulated the discharge reaction pathway that improves the performance of Li‐O2 battery. [ABSTRACT FROM AUTHOR]