Research and Progress of Inorganic Infrared Electrochromic Materials and Devices

BACKGROUND

Electrochromic materials can dynamically change their optical properties (such as transmittance, absorbance, and reflectance under the action of an applied voltage, and their research and application in the visible band have been widely concerned. In recent years, with the continuous development of electrochromic technology, the related research has been gradually extended to the infrared region.

OBJECTIVE

This invited review aims to provide an overview of the current status of several inorganic infrared electrochromic materials, to provide some references for future research, and to promote the research and application of electrochromic technology in the infrared region.

METHODS

This review summarizes various research results in the field of infrared electrochromic, which includes a detailed literature review and patent search. Starting from the key performance parameters and device structure characteristics of infrared electrochromic devices (ECDs), the research and progress of several types of inorganic infrared electrochromic materials, including metal oxides, plasma nanocrystals, and carbon nanomaterials, are mainly presented, and feasible optimization directions are also discussed.

CONCLUSION

We believe that the potential of these materials for civilian and military applications, for example, infrared electrochromic smart windows, infrared stealth/disguise, and thermal control of spacecraft, can be fully exploited by optimizing the materials and their devices to improve their performance.

Self-evolved BOx anchored on Mg2B2O5 crystallites for high-performance oxidative dehydrogenation of propane

Oxidative dehydrogenation of propane (ODHP) is a promising process for producing propene. Recently, some boron-based catalysts have exhibited excellent olefin selectivity in ODHP. However, their complex synthetic routes and poor stability under high-temperature reaction conditions have hindered their practical application. Herein, we report a self-evolution method rather than conventional assembly approaches to acquire structures with excellent stability under a high propane conversion, from a single precursor-MgB2. The catalyst feasibly prepared and optimized exhibited a striking performance: 60% propane conversion with a 43.2% olefin yield at 535°C. The BOx corona pinned by the strong interaction with the borate enabled zero loss of the high conversion (around 40%) and olefins selectivity (above 80%) for over 100 h at 520°C. This all-in-one strategy of deriving all the necessary components from just one raw chemical provides a new way to synthesize effective and economic catalysts for potential industrial implementation.

On the structural and electrical properties of MgFe2O4, MgMn0.2Fe1.8O4, and Mn3O4

Charge carrier transport via donor/acceptor pairs of similar elements is dominant in n-type MgFe2O4 and p-type Mn3O4 spinels. The temperature-independent activation energy in the form of the nearest neighbor hopping model is applied for Fe2+/Fe3+ pairs of cubic MgFe2O4 spinel in the temperature range of 423-523 K (150-250 °C). At such high temperatures, even for this relatively narrow temperature range, the constant energy barrier deviates to a variable range hopping energy barrier in the case of Mn3O4, due to Jahn-Teller active octahedral sites. Replacing 10 mol% of Fe at octahedral sites with Mn has significantly increased the electron hopping energy barrier and electrical conductivity of MgFe2O4, while keeping the nearest neighbor hopping model dominant. The observed high energy barrier is due to donor/acceptor pairs of different elements (Mn/Fe). Due to a lack of structural distortion, deviation from the nearest neighbor hopping mechanism with temperature-independent activation energy was not observed. Rietveld refined XRD patterns and FT-IR spectra are utilized to support the argument on electrical conductivity mechanisms.

Multitudinous components recovery, heavy metals evolution and environmental impact of coal gasification slag: A review

In recent years, the coal gasification industry has rapidly developed, becoming one of the most promising technologies in the advanced and clean coal chemical industry. As a result, the annual emission of coal gasification fine slag (CGFS) has continuously increased. The present situation of CGFS is regarded as a notorious waste in gasification plants and is rudely landfilled or deposited in slag yards, which leads to a large waste of land resources, the release of dangerous elements, and numerous pollution problems. Although CGFS is classified as industrial solid waste, its unique physical and chemical properties make it a valuable resource that cannot be overlooked. This paper focuses on the resource utilization technology and environmental impact of CGFS. The resource utilization of different components of CGFS has realized the evolution from waste to valuable substances. Moreover, during the disposal and utilization of CGFS, its environmental effects cannot be ignored. The main problems and future research directions are also further proposed. Efforts should be focused on the challenges of the technology, cost, and environmental protection in the application process to achieve industrial application, and ultimately committed to sustainable and green development goals, and promote the sustainable management and conservation of resources.

[Research progress on biocomposites based on bioactive glass]

Bioactive glass (BG) has been widely used in the preparation of artificial bone scaffolds due to its excellent biological properties and non-cytotoxicity, which can promote bone and soft tissue regeneration. However, due to the brittleness, poor mechanical strength, easy agglomeration and uncontrollable structure of glass material, its application in various fields is limited. In this regard, most current researches mainly focus on mixing BG with organic or inorganic materials by freeze-drying method, sol-gel method, etc., to improve its mechanical properties and brittleness, so as to increase its clinical application and expand its application field. This review introduces the combination of BG with natural organic materials, metallic materials and non-metallic materials, and demonstrates the latest technology and future prospects of BG composite materials through the development of scaffolds, injectable fillers, membranes, hydrogels and coatings. The previous studies show that the addition of BG improves the mechanical properties, biological activity and regeneration potential of the composites, and broadens the application of BG in the field of bone tissue engineering. By reviewing the recent BG researches on bone regeneration, the research potential of new materials is demonstrated, in order to provide a reference for future related research.

Next-generation ultrafiltration membranes: A review of material design, properties, recent progress, and challenges

Membrane technology utilizing ultrafiltration (UF) processes has emerged as the most widely used and cost-effective simple process in many industrial applications. The industries like textiles and petroleum refining are promptly required membrane based UF processes to alleviate the potential environmental threat caused by the generation of various wastewater. At the same time, major limitations such as material selection as well as fouling behavior challenge the overall performance of UF membranes, particularly in wastewater treatment. Therefore, a complete discussion on material design with structural property relation and separation performance of UF membranes is always exciting. This state-of-the-art review has exclusively focused on the development of UF membranes, the material design, properties, progress in separation processes, and critical challenges. So far, most of the review articles have examined the UF membrane processes through a selected track of paving typical materials and their limited applications. In contrast, in this review, we have exclusively aimed at comprehensive research from material selection and fabrication methods to all the possible applications of UF membranes, giving more attention and theoretical understanding to the complete development of high-performance UF systems. We have discussed the methodical engineering behind the development of UF membranes regardless of their materials and fabrication mechanisms. Identifying the utility of UF membrane systems in various applications, as well as their mode of separation processes, has been well discussed. Overall, the current review conveys the knowledge of the present-day significance of UF membranes together with their future prospective opportunities whilst overcoming known difficulties in many potential applications.

Nanoscale chemical and structural investigation of solid solution polyelemental transition metal oxide nanoparticles

Although it has been shown that configurational entropy can improve the structural stability in transition metal oxides (TMOs), little is known about the oxidation state of transition metals under random mixing of alloys. Such information is essential in understanding the chemical reactivity and properties of TMOs stabilized by configurational entropy. Herein, utilizing electron energy loss spectroscopy (EELS) technique in an aberration-corrected scanning transmission electron microscope (STEM), we systematically studied the oxidation state of binary (Mn, Fe)₃O₄, ternary (Mn, Fe, Ni)₃O₄, and quinary (Mn, Fe, Ni, Cu, Zn)₃O₄ solid solution polyelemental transition metal oxides (SSP-TMOs) nanoparticles. Our findings show that the random mixing of multiple elements in the form of solid solution phase not only promotes the entropy stabilization but also results in stable oxidation state in transition metals spanning from binary to quinary transition metal oxide nanoparticles.

Interception of fertile soil phosphorus leaching with immobilization materials: Recent progresses, opportunities and challenges

The non-point source pollution induced by phosphorus (P) leaching from fertile soils is accelerating the eutrophication phenomena in aqueous ecosystems. Herein, to alleviate and intercept the P leaching from the fertile soils, diverse P immobilization materials (PIM) which can transform labile P into stable P via a range of physicochemical and biological interactions have been adopted and received increasing research interest. However, the remediation mechanisms of different PIMs were complex and vary with soil properties and PIM application methods. In this review, the P fraction and mobility characteristics of different fertile soils were first introduced. Then, three kinds of PIM including inorganic materials (e.g., clay minerals and red mud), organic materials (e.g., polyacrylamide), and composites (e.g., modified biochar) applied in soil P leaching interception were concluded. The key factors (i.e., soil pH, soil texture, organic matter content and variable soil moisture) influencing PIM performance and potential PIMs used for reducing soil P leaching were also introduced. Current review can favor for proposing more suitable and insightful strategies to regulate the fertile soil P and achieve the dual goals of improving the crop land quality and yield, and preventing agricultural non-point source pollution.

Doping of Sn-based two-dimensional perovskite semiconductor for high-performance field-effect transistors and thermoelectric devices

Doping is an important technique for semiconductor materials and devices, yet effective and controllable doping of organic-inorganic halide perovskites is still a challenge. Here, we demonstrate a facile way to dope two-dimensional Sn-based perovskite (PEA)₂SnI₄ by incorporating SnI₄ in the precursor solutions. It is observed that Sn⁴⁺ produces p-doping effect on the perovskite, which increases the electrical conductivity by 10⁵ times. The dopant SnI₄ is also found to improve the film morphology of (PEA)₂SnI₄, leading to reduced trap states. This doping technique allows us to improve the room temperature mobility of (PEA)₂SnI₄ field-effect transistors from 0.25 to 0.68 cm² V^-1 s^-1 thanks to reduced trapping effects in the doped devices. Moreover, the doping technique enables the characterization and improvement of the thermoelectric performance of (PEA)₂SnI₄ films, which show a high power factor of 3.92 μW m^-1 K^-2 at doping ratio of 5 mol %.

Ultrafast spectroscopy studies of carrier dynamics in semiconductor nanocrystals

Semiconductor nanocrystals have become ubiquitous both in scientific research and in applied technologies related to light. When a nanocrystal absorbs a photon an electron-hole pair is created whose fate dictates whether the nanocrystal will be suitable for a particular application. Ultrafast spectroscopy provides a real-time window to monitor the evolution of the electron-hole pair. In this review, we focus on CdSe nanocrystals, the most-studied nanocrystal system to date, and also highlight ultrasmall nanocrystals, “standard nanocrystals” of different binary composition, alloyed nanocrystals, and core/shell nanocrystals and nanorods. We focus on four time-resolved spectroscopies used to interrogate nanocrystals: pump-probe, fluorescence upconversion, time-correlated single photon counting, and non-linear spectroscopies. The basics of the nanocrystals and the spectroscopies are presented, followed by a detailed synopsis of ultrafast spectroscopy studies performed on the various semiconductor nanocrystal systems.

Metal halide perovskite toxicity effects on Arabidopsis thaliana plants are caused by iodide ions

Highly efficient solar cells containing lead halide perovskites are expected to revolutionize sustainable energy production in the coming years. Perovskites are generally assumed to be toxic because of the lead (Pb), but experimental evidence to support this prediction is scarce. We tested the toxicity of the perovskite MAPbI₃ (MA = CH₃NH₃) and several precursors in Arabidopsis thaliana plants. Both MAPbI₃ and the precursor MAI hamper plant growth at concentrations above 5 μM. Lead-based precursors without iodide are only toxic above 500 μM. Iodine accumulation in Arabidopsis correlates with growth inhibition at much lower concentrations than lead. This reveals that perovskite toxicity at low concentrations is caused by iodide ions specifically, instead of lead. We calculate that toxicity thresholds for iodide, but not lead, are likely to be reached in soils upon perovskite leakage. This work stresses the importance to further understand and predict harmful effects of iodide-containing perovskites in the environment.

The apparent surface free energy of rare earth oxides is governed by hydrocarbon adsorption

The surface free energy of rare earth oxides (REOs) has been debated during the last decade, with some reporting REOs to be intrinsically hydrophilic and others reporting hydrophobic. Here, we investigate the wettability and surface chemistry of pristine and smooth REO surfaces, conclusively showing that hydrophobicity stems from wettability transition due to volatile organic compound adsorption. We show that, for indoor ambient atmospheres and well-controlled saturated hydrocarbon atmospheres, the apparent advancing and receding contact angles of water increase with exposure time. We examined the surfaces comprehensively with multiple surface analysis techniques to confirm hydrocarbon adsorption and correlate it to wettability transition mechanisms. We demonstrate that both physisorption and chemisorption occur on the surface, with chemisorbed hydrocarbons promoting further physisorption due to their high affinity with similar hydrocarbon molecules. This study offers a better understanding of the intrinsic wettability of REOs and provides design guidelines for REO-based durable hydrophobic coatings.

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REOs are intrinsically hydrophilic but become hydrophobic as they adsorb hydrocarbons

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Our results demonstrate that both physisorption and chemisorption occur on the surface

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The adsorption of hydrocarbons was confirmed by multiple surface chemistry analysis

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Our work offers a better fundamental understanding of the intrinsic wettability of REO

Probing atomic structure of beam-sensitive energy materials in their native states using cryogenic transmission electron microscopes

Organic-inorganic hybrid perovskite nanoplatelets (NPLs) have emerged as promising materials for solar energy. However, the structural instability under electron beam hinders further probing and understanding of its crystalline structures and defects at the atomic scale. Taking methylammonium bromide perovskite methylammonium lead bromide (CH₃NH₃PbBr₃ (MAPbBr₃)) perovskite NPLs as model material, we performed atomic-scale characterization of the native state of the hybrid perovskite solar cell material in different states using ultra-low-dose cryo-TEM imaging. With a series of observation at different growth time, we revealed the growth pattern of such MAPbBr₃ material from an initially stacked slices with rotational moiré fringes to a perfect single-crystalline structure of NPLs. Our high-resolution cryo-TEM further enabled the atomic-scale investigations of solid electrolyte interphase (SEI) and sodium (Na) dendrite materials, which can largely impact the safety and life of batteries. This study offers insights on the atomic scale characterization of a wide variety of beam-sensitive materials, inspiring us to probe more materials with cryo-transmission electron microscopes (TEM).

Sonochemical fabrication of inorganic nanoparticles for applications in catalysis

Catalysis covers almost all the chemical reactions or processes aiming for many applications. Sonochemistry has emerged in designing and developing the synthesis of nano-structured materials, and the latest progress mainly focuses on the synthetic strategies, product properties as well as catalytic applications. This current review simply presents the sonochemical effects under ultrasound irradiation, roughly describes the ultrasound-synthesized inorganic nano-materials, and highlights the sonochemistry applications in the inorganics-based catalysis processes including reduction, oxidation, degradation, polymerization, etc. Or all in all, the review hopes to provide an integrated understanding of sonochemistry, emphasize the great significance of ultrasound-assisted synthesis in structured materials as a unique strategy, and broaden the updated applications of ultrasound irradiation in the catalysis fields.

Deep-Breathing Honeycomb-like Co-Nx-C Nanopolyhedron Bifunctional Oxygen Electrocatalysts for Rechargeable Zn-Air Batteries

Metal organic framework (MOF) derivatives have been extensively used as bifunctional oxygen electrocatalysts. However, the utilization of active sites is still not satisfactory owing to the sluggish mass transport within their narrow pore channels. Herein, interconnected macroporous channels were constructed inside MOFs-derived Co-N_x-C electrocatalyst to unblock the mass transfer barrier. The as-synthesized electrocatalyst exhibits a honeycomb-like morphology with highly exposed Co-N_x-C active sites on carbon frame. Owing to the interconnected ordered macropores throughout the electrocatalyst, these active sites can smoothly “exhale/inhale” reactants and products, enhancing the accessibility of active sites and the reaction kinetics. As a result, the honeycomb-like Co-N_x-C displayed a potential difference of 0.773 V between the oxygen evolution reaction potential at 10 mA cm⁻² and the oxygen reduction reaction half-wave potential, much lower than that of bulk-Co-N_x-C (0.842 V). The rational modification on porosity makes such honeycomb-like MOF derivative an excellent bifunctional oxygen electrocatalyst in rechargeable Zn-air batteries.

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A deep-breathing oxygen electrocatalyst with highly dispersed active sites was built

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Sculpturing ordered macropores in MOF derivatives enables fast mass transport

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The honeycomb-like Co-N_x-C nanopolyhedron worked well in rechargeable Zn-air battery

Improving the biocatalytic performance of co-immobilized cells harboring nitrilase via addition of silica and calcium carbonate

To improve nicotinic acid (NA) yield and meet industrial application requirements of sodium alginate-polyvinyl alcohol (SA-PVA) immobilized cells of Pseudomonas putida mut-D3 harboring nitrilase, inorganic materials were added to the SA-PVA immobilized cells to improve mechanical strength and mass transfer performance. The concentrations of inorganic materials were optimized to be 2.0% silica and 0.6% CaCO₃. The optimal pH and temperature for SA-PVA immobilized cells and composite immobilized cells were both 8.0 and 45 °C, respectively. The half-lives of composite immobilized cells were 271.48, 150.92, 92.92 and 33.12 h, which were 1.40-, 1.35-, 1.22- and 1.63-fold compared to SA-PVA immobilized cells, respectively. The storage stability of the composite immobilized cells was slightly increased. The composite immobilized cells could convert 14 batches of 3-cyanopyridine with feeding concentration of 250 mM and accumulate 418 g ·L^-1 nicotinic acid, while the SA-PVA immobilized cells accumulated 346 g L^-1 nicotinic acid.

Optically stimulated luminescence study in rare earth doped SrBPO5

Optically stimulated luminescence (OSL) was studied in rare earth doped SrBPO₅ for the possible applications in radiation dosimetry using optically stimulated luminescence. The study shows that the sensitivity of the Eu doped SrBPO₅ shows good OSL and the sensitivity is comparable to that of Al₂O₃:C. It is observed that annealing has a profound effect on the OSL sensitivity. Slowly cooled Eu doped sample shows highest sensitivity and is 77% compared to that Al₂O₃:C whereas lowest sensitivity is observed in the quenched sample. Other properties like good linearity and low fading will make this phosphor suitable for the applications in radiation dosimetry using OSL.

Effect of organic ligands (L-Proline and L-Methionine) on growth, structural, vibrational, crystalline perfection, SHG efficiency, microscopic and optical properties of KDP single crystals

The effect of L-Proline (LP) and L-Methionine (LM) doping on the various properties of KDP single crystals grown by slow evaporation solution technique has been investigated. The external morphology of the grown crystals was found to vary due to different dopants and doping concentrations. The change in powder X-ray diffraction intensity patterns due to doping shows the lattice distortion within resolution limit and confirms that there is no extra phase. Further, the same was confirmed by FT-Raman analysis. Infra red microscopic study also exhibits the effectiveness of doping in terms of varying surface morphology. Crystalline perfection of KDP crystals with LP and LM doping was examined by high-resolution X-ray diffraction. This shows very interesting features on the ability of accommodating the dopants in the crystalline matrix. Second harmonic generation efficiency was also found to be in similar fashion as of crystalline perfection. The optical transparency of doped crystals was tested.

SAXS in inorganic and bioinspired research

In situ and time-resolved structural information about emergent microstructures that progressively develop during the formation of inorganic or biologically mediated solid phases from solution is fundamental for understanding of the mechanisms driving complex precipitation reactions, for example, during biomineralization. In this brief chapter, we present the use of small- and wide-angle X-ray scattering (SAXS and WAXS) techniques and show how SAXS can be used to gather structural information on the nanoscale properties of the de novo-forming entities. We base the discussion on several worked examples of inorganic materials such as calcium carbonate, silica, and perovskite-type titanates.

Structural features of two novel alluaudite-like arsenates Cd1.16Zn2.34(AsO4)1.5(HAsO4)(H2AsO4)0.5 and Cd0.74Mg2.76(AsO4)1.5(HAsO4)(H2AsO4)0.5

Two new compounds, Cd1.16Zn2.34(AsO4)1.5(HAsO4)(H2AsO4)0.5 (1) and Cd0.74Mg2.76(AsO4)1.5(HAsO4)(H2AsO4)0.5 (2), have been prepared hydrothermally. Their crystal structures consist of chains of edge-sharing M1O4(OH0.5)2, M1aO4(OH0.5)2, M2O5(OH0.5), and M2aO5(OH0.5) octahedra (M1, M1a = Zn, Cd; M2, M2a = Zn for 1, and M1, M1a = Mg, Cd; M2, M2a = Mg for 2) that are stacked parallel to (1 0 1) and are connected by the [(AsO4)0.5(AsO3(OH))0.5]2.5- and [(AsO4)0.5(AsO2(OH)2)0.5]2- tetrahedra. These chains produce two types of channels parallel to the c-axis. Cd atoms are located in channels 2, while in channels 1 are situated hydrogen atoms of OH groups. The infrared spectra clearly show the presence of broad O-H stretching and bending vibrations centred at 3236, 2392 1575 and 1396 cm-1 in (1), and 3210, 2379 1602 and 1310 cm-1 in (2). The O-H stretching frequency is in good agreement with O⋯O distances. Furthermore, structural characteristics of compounds with similar alluaudite-like structures were discussed.