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Ferroelectric materials have important applications in transduction, data storage, and nonlinear optics. Inorganic ferroelectrics such as lead zirconate titanate possess large polarization, though they are rigid and brittle. Ferroelectric polymers are light weight and flexible, yet their polarization is low, bottlenecked at 10 μC cm−2. Here we show poly(vinylidene fluoride) nanocomposite with only 0.94% of self-nucleated CH3NH3PbBr3 nanocrystals exhibits anomalously large polarization (~19.6 μC cm−2) while retaining superior stretchability and photoluminance, resulting in unprecedented electromechanical figures of merit among ferroelectrics. Comprehensive analysis suggests the enhancement is accomplished via delicate defect engineering, with field-induced Frenkel pairs in halide perovskite stabilized by the poled ferroelectric polymer through interfacial coupling. The strategy is general, working in poly(vinylidene fluoride-co-hexafluoropropylene) as well, and the nanocomposite is stable. The study thus presents a solution for overcoming the electromechanical dilemma of ferroelectrics while enabling additional optic-activity, ideal for multifunctional flexible electronics applications. Wang et al. report large nonvolatile polarization in stretchable polymer ferroelectrics incorporating perovskite nanocrystals. The built-in electric field from poled ferroelectrics stabilises Frenkel defects via interfacial coupling, which can also enhance the polarization of nonferroelectrics. [ABSTRACT FROM AUTHOR]

Quasi‐two‐dimensional (quasi‐2D) perovskites are emerging as efficient emitters in blue perovskite light‐emitting diodes (PeLEDs), while the imbalanced crystallization of the halide‐mixed system limits further improvements in device performance. The rapid crystallization caused by Cl doping produces massive defects at the interface, leading to aggravated non‐radiative recombination. Meanwhile, unmanageable perovskite crystallization is prone to facilitate the formation of nonuniform low‐dimensional phases, which results in energy loss during the exciton transfer process. Here, we propose a multifunctional interface engineering for nucleation and phase regulation by incorporating the zwitterionic additive potassium sulfamate into the hole transport layer. By using potassium ions (K+) as heterogeneous nucleation seeds, finely controlled growth of interfacial K+‐guided grains is achieved. The sulfamate ions can simultaneously regulate the phase distribution and passivate defects through coordination interactions with undercoordinated lead atoms. Consequently, such synergistic effect constructs quasi‐2D blue perovskite films with smooth energy landscape and reduced trap states, leading to pure‐blue PeLEDs with a maximum external quantum efficiency (EQE) of 17.32 %, spectrally stable emission at 478 nm and the prolonged operational lifetime. This work provides a unique guide to comprehensively regulate the halide‐mixed blue perovskite crystallization by manipulating the characteristics of grain‐growth substrate. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting diodes (PeLEDs) are emerging as promising candidates for new‐generation high‐definition displays with excellent color purity and low power consumption. Nevertheless, the massive defects at grain boundaries and severe interfacial exciton quenching are critical challenges that hinder the commercialization process of PeLEDs. Herein, a novel and feasible strategy of interfacial molecule control is demonstrated by employing a bifunctional material with abundant phosphine oxide groups to induce strong interaction and exciton management between the perovskite and electron‐transport layers (ETLs). This modification layer is capable of passivating the surface crystal defects and blocking the interfacial exciton transfer simultaneously, contributing to minimized energy loss at the interface. Consequently, the modified PeLEDs with green (at 513 nm), blue (at 488 nm), and red (at 666 nm) emissions achieve maximum external quantum efficiencies of 18.8%, 12.6%, and 12.3%, respectively. This study reveals the importance of interfacial molecule control for reducing the energy loss in PeLEDs. [ABSTRACT FROM AUTHOR]

Perovskite Light‐emitting diodes (PeLEDs) have emerged as a promising technique for future high‐definition displays due to their outstanding electroluminescent characters. However, the development of blue PeLEDs toward practical applications is seriously hindered by their inferior performance, which mainly arises from the detrimental halide ionic behavior and thus severe nonradiative recombination in mixed‐halide blue perovskite materials. Herein, efficient sky‐blue PeLEDs featuring spectrally stable emission at 483 nm are realized by employing bifunctional passivators of Lewis‐base benzoic acid anions and alkali metal cations to simultaneously passivate the under‐coordinated lead atoms and suppress halide ion migration. A decent external quantum efficiency (EQE) of 16.58% and a maximum EQE of 18.65% are achieved, which is further boosted to 28.82% through the optical outcoupling enhancement. This work demonstrates unique insight into the generality and individuality of this category of benzoates and puts forward a feasible guidance in choosing appropriate additives for efficient perovskite materials. [ABSTRACT FROM AUTHOR]

Sn‐based perovskite materials are promising lead‐free alternatives in thin film photodetectors (PDs) for applications such as optical communications, night visions and biomedical near‐infrared imaging systems. However, constructing Sn‐based photodetectors with high sensitivity, ultrafast response, and good operation stability has been a challenge. Herein, the phenyl‐ethyl ammonium (PEA+) additive is introduced in pristine FASnI3, which regulates the thin film growth, passivates the trap/defect states, prevents Sn2+/Sn4+oxidation, and releases the crystal strain. The Resulting FA0.8PEA0.2SnI3 thin films exhibit highly crystalline order and flexibility. A self‐powered PD using FA0.8PEA0.2SnI3 as the active layer demonstrates excellent responsivity of 0.262 W−1, detectivity of 2.3 × 1011 Jones. And it possesses the fastest rise and decay time of 25 µs and 42 µs as compared with the state‐of‐art Sn‐based perovskite PDs. The transient absorption spectroscopy analysis validates greatly reduced trapping states and defects of FASnI3 with the PEA+ film for ultrafast response. A flexible Sn‐based perovskite PD without any encapsulation in air continuously shows ultrafast responses after 10,000 bending cycles. Meanwhile, a flexible imaging system can be realized by a 5 × 5 PD array with good sensing results. This study shows great potential in nontoxic and ultrafast Sn‐based perovskite PDs for flexible imaging applications. [ABSTRACT FROM AUTHOR]

Reduced‐dimensional perovskite light‐emitting diodes (PeLEDs) have shown great potential in solution‐processed high‐definition displays. However, the inferior electroluminescent (EL) performance of blue PeLEDs has become a huge challenge for their commercialization. The inefficient domain control [number of PbX6− layers (n)] and deleterious phase segregation make the blue PeLEDs suffer from low EL efficiency and poor spectral stability. Here, a rational strategy for perovskite crystallization control by adjusting the precursor concentration is proposed for improving phase distribution and suppressing ion migration in reduced‐dimensional mixed‐halide blue perovskite films. Based on this method, efficient sky‐blue PeLEDs exhibit a maximum external quantum efficiency (EQE) of 8.5% with stable EL spectra at 482 nm. Additionally, spectrally stable pure‐blue PeLEDs at 474 and 468 nm are further obtained with maximum EQEs of 4.0% and 2.4%, respectively. These findings may provide an alternative scheme for manipulating perovskite crystallization dynamics toward efficient and stable PeLEDs. [ABSTRACT FROM AUTHOR]

Halide perovskite materials are emerging as a new promising semiconductor display material owing to their excellent optical and electrical properties. Highly efficient blue perovskite light‐emitting diodes (PeLEDs) are the basis for full‐color displays and solid‐state lighting applications, but their efficiency and stability still lag far behind the red and green analogs. This review focuses on the key effect factors and novel strategies for blue emission PeLEDs. In detail, first effective strategies to obtain blue emission perovskite are discussed, and then the recent progress and strategies in blue emission PeLEDs, including the physical properties and significant improvements based on different structural perovskite materials are systematically elucidated. Finally, the main challenges relating to efficiency, stability, lead toxicity, and fabrication techniques in blue emission PeLEDs are summarized, and the promising research avenues in the future are discussed. [ABSTRACT FROM AUTHOR]

The development of inorganic hole‐transporting materials (HTMs) is one of the most reliable ways to improve the stability of perovskite solar cells (PSCs). However, the un‐optimal buried interfacial contacts and the defects located at the inorganic HTMs/perovskite interface restricted the device's performance. Herein, a phase‐pure CuScO2 has been synthesized and further employed as mesoporous HTM in inverted PSCs. Surprisingly, a facile pretreatment of the hole‐transport layer by a formamidine salt compensates the I− vacancy of the buried perovskite film, thus regulating the interfacial band energy alignment between the HTM and perovskite. This ion compensation strategy can not only in situ repair the ion loss and improve the built‐in electric field, but also decrease the charge injection barrier and suppress the non‐radiative interfacial recombination. Benefiting from these merits, the resulting methylammonium‐free (MA), Cs/FA‐based PSCs displays a power conversion efficiency (PCE) of 22.42% along with excellent thermal and light stability. Moreover, the pre‐buried treatment strategy can be extended to MA‐containing CsFAMA triple‐cation perovskite film, and a champion inverted device delivers a PCE of 23.11%. This study offers a new avenue to the rational design of HTMs for highly efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting didoes (PeLEDs) have shown considerable potential in solution‐processable display applications. However, the performance of blue PeLEDs in terms of efficiency and stability hinders their practicality on account of severe trap‐mediated nonradiative recombination losses and halide phase segregation. To ameliorate these issues, mixed‐halide sky‐blue perovskite materials are strategically modulated through crystal defect passivation with a trifurcate isocyanate oligomer, which leads to the synergistical suppression of charge trap density and halide ion migration. The proposed approach enables the performance improvement for sky‐blue PeLEDs, exhibiting a peak external quantum efficiency of 14.82% and spectrally stable emission at 487 nm. In addition, prolonged operational lifetime and enhanced capability of moisture resistance are achieved simultaneously, approaching a half‐lifetime of ≈2900 s at an initial brightness of 178 cd m–2. [ABSTRACT FROM AUTHOR]

Quasi‐2D metal halide perovskite light emitting diodes (PeLEDs) have attracted a lot of attentions in recent years, while their potential applications in displays and lighting are limited by the device stability. Although defect passivation in PeLEDs is an effective method to ameliorate the unstable problem, the underlying mechanisms need to be further explored. Herein, organic spacer cations with different charge distributions and formation energies in quasi‐2D CsPbBr3 perovskites are utilized to unravel the defect passivation mechanisms, including phenylmethanamine, 2‐phenylethanamine bromide, and 4‐phenylbutylammonium. The experimental findings and density functional theory calculation reveal that the defect passivation occurs by the electrostatic interaction between defective PbBr64− octahedrons and proper organic spacer cations during the annealing process, particularly at the grain boundaries. The thermal stability of the perovskite films and device performance are improved after the effective defect passivation process. The exploration of the defect passivation process in perovskites will be beneficial to the development of high‐performance PeLEDs. [ABSTRACT FROM AUTHOR]

Regardless of the rapid advance on perovskite light‐emitting diodes (PeLEDs), the lack of long‐term operational stability hinders the practicality of this technology. Particularly, thermal management is indispensable to control the Joule heating induced by charge transport and parasitic re‐absorption of internally confined photons. Herein, a synergetic device architecture is proposed for minimizing the optical energy losses in PeLEDs toward high efficiency and long lifetime. By adopting a carefully modified perovskite emitter in combination with an improved light outcoupling structure, red PeLEDs emitting at 666 nm achieve a peak external quantum efficiency of 21.2% and an operational half‐lifetime of 4806.7 h for an initial luminance of 100 cd m‐2. The enhanced light extraction from trapped modes can efficiently reduce the driving current and suppress optical energy losses in PeLEDs, which in turn ameliorate the heat‐induced device degradation during operation. This work paves the way toward high‐performance PeLEDs for display and lighting applications in the future. [ABSTRACT FROM AUTHOR]

Efficient and stable blue emission of perovskite light‐emitting diodes (PeLEDs) is a requisite toward their potential applications in full‐color displays and solid‐state lighting. Rational manipulation over the entire electroluminescence process is promising to break the efficiency limit of blue PeLEDs. Herein, a facile device architecture is proposed to achieve efficient blue PeLEDs for simultaneously reducing the energetic loss during electron‐photon conversion and boosting the light outcoupling. Effective interfacial engineering is employed to manipulate the perovskite crystallization nucleation, enabling highly compact perovskite nanocrystal assemblies and suppressing the trap‐induced carrier losses by means of interfacial hydrogen bonding interactions. This strategy contributes to a high external quantum efficiency (EQE) of 12.8% for blue PeLEDs emitting at 486 nm as well as improved operational stability. Moreover, blue PeLEDs reach a peak EQE of 16.8% with the incorporation of internal outcoupling structures for waveguided light, which can be further raised to 27.5% by integrating a lens‐based structure for substrate‐mode light. These results verify the validity of this strategy in producing efficient and stable blue PeLEDs for practical applications. [ABSTRACT FROM AUTHOR]

While tremendous progress has recently been made in perovskite light‐emitting diodes (PeLEDs), large‐area blue devices feature inferior performance due to uneven morphologies and vast defects in the solution‐processed perovskite films. To alleviate these issues, a facile and reliable interface engineering scheme is reported for manipulating the crystallization of perovskite films enabled by a multifunctional molecule 2‐amino‐1,3‐propanediol (APDO)‐triggered "anchoring effect" at the grain‐growth interface. Sky‐blue perovskite films with large‐area uniformity and low trap states are obtained, showing the distinctly improved radiative recombination and hole‐transport capability. Based on the APDO‐induced interface engineering, synergistical boost in device performance is achieved for large‐area sky‐blue PeLED (measuring at 100 mm2) with a peak external quantum efficiency (EQE) of 9.2% and a highly prolonged operational lifetime. A decent EQE up to 6.1% is demonstrated for the largest sky‐blue device emitting at 400 mm2. [ABSTRACT FROM AUTHOR]

Metal halide perovskites are one of the most promising materials for optoelectronic applications owing to their unique optoelectronic properties. In the pursuit of achieving the efficient perovskite light‐emitting diodes (PeLEDs), the critical role of crystallization dynamics on luminescence properties of cesium lead bromide (CsPbBr3) perovskite films has been clarified based on the characterizations of in situ photoelectron spectroscopy, synchrotron‐based grazing incidence X‐ray diffraction, and device fabrication. The crystallinity and crystal orientation of CsPbBr3 perovskite films has been effectively controlled when tuning the underlayer of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) with the ethanolamine modification. The fast crystallization with the formation of pure cubic phase (α‐CsPbBr3) reveals a substantial boost in luminance and device efficiency of PeLEDs, whereas the performance degradation occurs due to the phase transition from α‐CsPbBr3 to orthogonal phase (γ‐CsPbBr3) along with the appearance of PbBr2. The decomposition of organic additives in the perovskite films is a key factor that results in this phase transition, which changes the absorption and band gap as confirmed by the density functional theory calculation. These experimental and theoretical findings provide a better understanding of the crystallization dynamics of perovskite emitters and their influence on device performance by tuning the substrate properties. [ABSTRACT FROM AUTHOR]

Perovskite light‐emitting diodes (PeLEDs) are emerging candidates for the applications of solution‐processed full‐color displays. However, the device performance of deep‐blue PeLED still lags far behind that of their red and green counterparts, which is largely limited by low external quantum efficiency (EQE) and poor operational stability. Here, a facile and reliable crystallization strategy for perovskite grains is proposed, with improved deep‐blue emission through rational interfacial engineering. By modifying the substrate with potassium cation (K+) as the supplier of heterogeneous nucleation seeds, the interfacial K+‐guided grain growth is realized for well‐packed perovskite assemblies with high surface coverage and the controlled crystal orientation, leading to the enhanced radiative recombination and hole‐transport capabilities. Synergistical boost in device performance is achieved for deep‐blue PeLEDs emitting at 469 nm with a peak EQE of 4.14%, a maximum luminance of 451 cd m–2, and spectrally stable color coordinates of (0.125, 0.076) that matches well with the National Television System Committee (NTSC) standard blue. [ABSTRACT FROM AUTHOR]

Abstract Chemical-looping steam methane reforming (CL-SMR) is a novel technology for syngas and hydrogen production without purification process. A series of three-dimensionally ordered macroporous (3DOM) LaFe 1− x Ni x O 3 (x = 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) perovskite-type oxides were synthesized using the polystyrene colloidal crystal templating method. The structural and physico-chemical properties of the obtained oxides were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauere-Emmette-Teller (BET) surface area technologies. The structure-reactivity relationships and effects of Ni-substitution on the improvement of reactivity and resistance to carbon formation were investigated in a thermo-gravimetric analyzer and a fixed-bed reactor. It was found that the as-prepared oxides obtained standard perovskite structures and the well-ordered skeleton was surrounded with uniform close-packed macroporous windows. Ni-substitution improved the ability for oxygen supply but simultaneously enhanced the methane dissociation. While the openness channel and large surface area of 3DOM perovskite allowed low mass-transfer resistances and provided high active sites for reaction. Complicated factors synergistically affected the reactivity and an optimal value for Ni-substitution is confirmed with x = 0.1 by comprehensively considering from the points of reactivity, resistance to carbon formation, as well as hydrogen generation capacity. During the following successive redox reactions, 3DOM LaFe 0.9 Ni 0.1 O 3 exhibited good regenerability and thermo-stability probably converting 90% of CH 4 into syngas in methane reforming stage and generating ∼210–220 ml hydrogen in steam splitting stage. Highlights • The synthesized perovskites exhibit three-dimensional frameworks. • Openness channel promotes mass-transfer and provides more active sites. • Ni-substitution enhances the resistance toward carbon deposition formation. • Performance of 3DOM LaFe 0.9 Ni 0.1 O 3 stays stable during successive redox cycles. [ABSTRACT FROM AUTHOR]

Pure perovskite BiFeO3, sillenite Bi2 Fe4 O9, and BiFeO3/ Bi2 Fe4 O9 were synthesized facilely by controlling the precursor Bi/ Fe ion ratio through a hydrothermal method. The phase composition, morphology, optical properties, and photocatalytic activity of as-prepared samples were investigated in detail. Our results indicate that the morphology and properties of products strongly dependent on the precursor Bi/Fe ion ratio. Photocatalysis of Congo Red reveals that sillenite Bi2 Fe4 O9 shows superior activity to perovskite BiFeO3, and BiFeO3/ Bi2 Fe4 O9 exhibited higher activity with 71.45% degradation rate in 90 min. It provides an easy and efficient way to tune the composition and photocatalytic activity of Bi-based oxides. [ABSTRACT FROM AUTHOR]

Deep-Blue Emission: Interfacial Potassium-Guided Grain Growth for Efficient Deep-Blue Perovskite Light-Emitting Diodes (Adv. Funct. Keywords: crystallization manipulation; deep-blue emission; interface engineering; perovskite light-emitting diodes EN crystallization manipulation deep-blue emission interface engineering perovskite light-emitting diodes 1 1 1 02/05/21 20210203 NES 210203 In article number 2006736, Yan-Qing Li, Jian-Xin Tang, and co-workers demonstrate a facile and reliable crystallization strategy for interfacial potassium-guided perovskite grain growth, leading to efficient deep-blue light-emitting diodes with an external quantum efficiency of 4.14% and stable color coordinates of (0.125, 0.076). Crystallization manipulation, deep-blue emission, interface engineering, perovskite light-emitting diodes. [Extracted from the article]

The thermal conductivity of c-axis textured polycrystalline perovskite Bi4Ti3O12 and random polycrystalline material is reported up to 1000 °C. Based on measurements of the thermal diffusivity, density, and specific heat, the thermal conductivity is lower along the c-axis than in the a-b plane by almost a factor of 2, and the anisotropy persists up to at least 1000 °C despite a change in the crystal structure at 675 °C. The exceptionally low (1.0 W/mK), temperature-independent conductivity perpendicular to the perovskite layer structure is attributed to the density difference between the pseudoperovskite and fluorite blocks in the unit cell, forming a natural nanostructured superlattice. [ABSTRACT FROM AUTHOR]

Inorganic mixed‐halide CsPbX3‐based perovskite solar cells (PeSCs) are emerging as one of the most promising types of PeSCs on account of their thermostability compared to organic–inorganic hybrid counterparts. However, dissatisfactory device performance and high processing temperature impede their development for viable applications. Herein, a facile route is presented for tuning the energy levels and electrical properties of sol–gel‐derived ZnO electron transport material (ETM) via the doping of a classical alkali metal carbonate Cs2CO3. Compared to bare ZnO, Cs2CO3‐doped ZnO possesses more favorable interface energetics in contact with the CsPbI2Br perovskite layer, which can reduce the ohmic loss to a negligible level. The optimized PeSCs achieve an improved open‐circuit voltage of 1.28 V, together with an increase in fill factor and short‐circuit current. The optimized power conversion efficiencies of 16.42% and 14.82% are realized on rigid glass substrate and flexible plastic substrate, respectively. A high thermostability can be simultaneously obtained via defect passivation at the Cs2CO3‐doped ZnO/CsPbI2Br interface, and 81% of the initial efficiency is retained after aging for 200 h at 85 °C. [ABSTRACT FROM AUTHOR]

In article number 1801534, Yan‐Qing Li, Feng Gao, Chun‐Sing Lee, Jian‐Xin Tang, and co‐workers propose a method for the synergetic morphology control over cesium lead bromide perovskite films. Bright perovskite light‐emitting diodes (PeLEDs) are achieved due to the synergetic interplay of small grain sizes for efficient energy funneling and defect passivation for suppressing nonradiative recombination losses. Efficient flexible PeLEDs on plastics are also realized, showing great potential for commercially viable applications. [ABSTRACT FROM AUTHOR]

Here, Nb5+ were partially substituted for Ta5+ in the double perovskite Sr 2 ScTaO 6 : Cr3+ phosphor to improve its luminescence performance and finally obtained the optimized phosphor Sr 2 ScTa 0.6 Nb 0.4 O 6 : Cr3+. The structure, substitution mechanism, luminescence optimization mechanism, crystal field, and thermal stability of the phosphor were all thoroughly explored. The results indicate that introducing Nb5+ into Sr 2 ScTaO 6 : Cr3+ can cause lattice distortion in the host, and the distorted crystal lattice can break the forbidden transition of Cr3+, thereby enhancing its absorption of excitation light. At the same time, the full width at half maximum of the phosphor emission increased from 176.4 nm to 179.7 nm. And the internal quantum efficiency, absorption efficiency, and external quantum efficiency of the optimized Sr 2 ScTa 0.6 Nb 0.4 O 6 : Cr3+ phosphor can reach 86.3%, 49% and 42.3%, respectively. The photoelectric conversion efficiency of the optimized pc-LED increased from 5.63% to 7.80%@100 mA, indicating the introduction of Nb5+ in Sr 2 ScTaO 6 : Cr3+ improved the luminescence performance of phosphor. The above results provide directions for the development of more efficient and promising double-perovskite NIR phosphors. • Introducing Nb5+ can increase lattice distortion, thereby enhancing the absorption of excitation by the phosphors. • Nb5+ ion substitution can enhance the intensity, full width at half maximum, and quantum efficiency of emission. • The pc-LED synthesized from the optimized phosphors can improve the photoelectric conversion efficiency. [ABSTRACT FROM AUTHOR]

Co-production of syngas and hydrogen via chemical looping steam methane reforming (CL-SMR) using double perovskite-type oxide La 1.6 Sr 0.4 FeCoO 6 as an oxygen carrier was studied. The reaction mechanisms, including the synergistic effects, the metal transitions, the oxygen diffusion and the migration of reaction boundary during the two-step reactions, were systematically investigated by the characterizations of the oxygen carriers at different reaction stages using XRD, XPS, H 2 -TPR and TG technologies. Meanwhile, isothermal reactions were carried out in a fixed-bed reactor to analysis the reaction products. Three reaction stages including the total oxidation of methane with the active adsorbed oxygen, partial oxidation of methane with the lattice oxygen, and the methane decomposition were identified, using the surface of the oxygen carrier particles as reaction boundary. A large number of syngas was generated due to the concordant of methane dissociation with the lattice oxygen diffusion, and the resistant to coke formation was enhanced effectively. In the steam dissociation stage, the deep reduced metals (Fe 2+ and Co 0 ) combining with the abundant oxygen vacancies provided enough active sites for the breakage of H O bond of H 2 O. The oxygen vacancies were neutralized immediately by the O atom, and the two H atoms combined together to form amounts of H 2 . These results suggested that, the positive roles displayed by the synergistic effects between multi-metals in double perovskite structure could effectively promote the partial oxidation of methane and steam splitting. It provides a potential way to develop more active oxygen carrier for CL-SMR to co-produce syngas and hydrogen by comprehensively considering the methane dissociation and the lattice oxygen diffusion. [ABSTRACT FROM AUTHOR]

Chemical looping steam methane reforming (CL-SMR) is a potential route to efficiently co-produce syngas and hydrogen. Development of oxygen carrier with high activity, good recyclability, strong resistance to carbon deposition and excellence capacity for steam splitting is highly desired for this process. The article investigated a novel and unique structure of double perovskite-type oxides La 1−x Sr x FeCoO 6 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) as oxygen carrier. XRD, XPS and H 2 -TPR technologies were adopted to characterize the physical and chemical properties of them. Meanwhile, isothermal reactions and cyclic redox reactions were carried out in a fixed-bed reactor to determine the influences of Sr-substitution on the reactivity of La 1−x Sr x FeCoO 6 . XRD results confirmed the formation of double perovskite crystal structure for all the samples, while substitution of Sr induced a certain degree of Fe/Co disorder generating oxygen vacancies and/or higher oxidation states of metal cations. Synergistic interactions between surface metal ions, such as Fe 4+ /Fe 5+ with Co 3+ which were detected by XPS, strongly enhance the reducibility of oxygen carriers. Three zones including total oxidation of methane by surface oxygen, partial oxidation of methane by lattice oxygen and carbon deposition were divided. Among the six samples with different substitution of Sr, La 0.6 Sr 0.4 FeCoO 6 exhibited the best oxygen transport ability, thermal stability, as well as capacity for hydrogen generation. A stable CH 4 conversion at ∼90% with desired H 2 /CO ratio at 2.0–2.5 in the methane reduction stage, and an average hydrogen yield at ∼5.9 mmol/g oxygen carrier with ∼93.8% of hydrogen concentration in the steam oxidation stage were obtained during twenty successive redox reactions, which made them very attractive for the purpose of chemical looping partial oxidation of carbon fuel in real applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The perovskite CaTiO 3 microcrystals doped with Yb/Nd were prepared via solid state reaction. • The prepared samples exhibit near-infrared emissions that increase with temperature. • These thermal coupled emission peaks were utilized to form a non-contact thermometer. • The optical thermometer possesses a good repeatability and sensitivity. The optical thermometer materials have drawn tremendous attention for their excellent performances, such as fast response, well-adapted, and non-contact. However, most phosphors present thermally quenched emissions, which greatly weakens temperature sensing. In this work, we synthesized Yb3+/Nd3+ codoped CaTiO 3 microcrystals by solid state reaction. Under the excitation of 980 nm, the developed perovskite particles present anti-Stokes emissions at the near-infrared range. More importantly, the near-infrared anti-Stokes emissions gradually get enhanced as the temperature rises. An optical ratiometric thermometer has been constructed based on the energy level transitions of Nd3+ ions (4F 7/2 /4F 5/2 →4I 9/2). On account of the thermally enhanced emissions, the prepared thermometer only needs 16 mW/mm2 power density, and has a relatively high sensitivity of 1.52 % K−1. Therefore, the prepared Yb3+/Nd3+ codoped CaTiO 3 crystal is a promising optical thermometer material with great application prospects. [ABSTRACT FROM AUTHOR]