Gel Precursor Research Articles

Physically Cross-Linked PVA Hydrogels as Potential Wound Dressings: How Freezing Conditions and Formulation Composition Define Cryogel Structure and Performance

Objectives: Hydrogels produced using the freeze–thaw method have demonstrated significant potential for wound management applications. However, their production requires precise control over critical factors including freezing temperature and the choice of matrix-forming excipients, for which no consensus on the optimal conditions currently exists. This study aimed to address this gap by evaluating the effects of the above-mentioned variables on cryogel performance. Methods: Mechanical properties, absorption capacity, and microstructure were assessed alongside advanced analyses using differential scanning calorimetry (DSC) and low-field nuclear magnetic resonance relaxometry (LF TD NMR). Results: The results demonstrated that fully hydrolyzed polyvinyl alcohol (PVA) with a molecular weight above 61,000 g/mol is essential for producing high-performance cryogels. Among the tested formulations, an 8% (w/w) PVA56–98 solution (Mw~195,000; DH = 98.0–98.8%) with 10% (w/w) propylene glycol (PG) provided the best balance of stretchability, durability, and low adhesion. Notably, while −25 °C is often used for cryogel preparation, freezing the gel precursor at −80 °C yielded superior results, producing materials with more open, interconnected structures and enhanced mechanical strength and elasticity—deviating from conventional practices. Conclusions: The designed cryogel prototypes exhibited functional properties comparable to or even surpassing commercial wound dressings, except for absorption capacity, which remained lower. Despite this, the cryogel prototypes demonstrated potential as wound dressings, particularly for use in dry or minimally exuding wounds. All in all, this study provides a comprehensive analysis of the physicochemical and functional properties of PVA cryogels, establishing a strong foundation for the development of advanced wound dressing systems.

Solubility-controlled early age hydration of carbonate-activated slag: Underlying mechanisms and acceleration via seeding

The low environmental impacts and good performance of carbonate-activated binders have attracted substantial interest, while their intrinsically delayed reaction and prolonged setting times constrain widespread implementation. This study aims to investigate the early-age reaction kinetics of carbonate-activated binders, elucidate the underlying mechanisms and propose controlling methods. Results reveal that hydrotalcite and C-A-S-H gel precursors rapidly reach supersaturation within hours, yet precipitation of these phases remains absent. This phenomenon, coupled with high Si/Ca ratios in the pore solution, exhibits characteristics that may contribute to the observed reaction delays. A prolonged induction period and lethargic strength development are observed owing to the lack of strength-giving phases. The hydrotalcite and C-A-S-H concentrations surpass their theoretical solubility thresholds due to rising ionic strength and salt-in effects. The addition of a pH-neutral layered double hydroxide salt accelerates the reaction, confirming seeding impacts control pore solution saturation limits, constituting the underlying accelerator mechanism.

Enhanced Homogeneity in Perovskite Photovoltaic Films via Antisolvent Extraction of a Methylamine-Based Gel Precursor.

Solution-processed perovskite solar cells (PSCs) are at the forefront of next-generation photovoltaics, exhibiting outstanding photoelectric performance and cost-effective manufacturing. However, the prevalent use of polar aprotic solvents such as N,N-dimethylformamide and dimethyl sulfoxide in the preparation of perovskite precursor solution hinders complete solvent removal during film formation. Their high boiling points and strong coordinating abilities lead to solvated intermediates and heterogeneous perovskite crystal nucleation, particularly in the absence of the antisolvent-assisted crystallization. To address this, we developed a methylamine (MA)-based gel dispersion system that significantly improves the uniformity of perovskite films. By employing ethyl acetate (EA) antisolvent extraction, the gel precursor is extracted from a solution of MAI and PbI2 in MA ethanol, which is then diluted in pure acetonitrile (ACN) solvent to form a clear perovskite precursor solution. Benefiting from the highly volatile nature of the ACN-based gel perovskite precursor solution and its rich concentration of high-valent PbIn2-n coordination compounds, this approach enables the fabrication of high-quality MAPbI3 perovskite films, yielding PCEs of 21.34% for PSC and 19.77% for a 5 × 5 cm2 mini-module. This MA-based gel perovskite precursor strategy offers a promising avenue for potential applications in the scalable manufacture of PSCs.

Development of Robust CuNi Bimetallic Catalysts for Selective Hydrogenation of Furfural to Furfuryl Alcohol under Mild Conditions

Furfuryl alcohol represents a pivotal intermediate in the high-value utilization of renewable furfural, derived from agricultural residues. The industrial-scale hydrogenation of furfural to furfuryl alcohol typically employs Cu-based catalysts, but their limited catalytic activity necessitates high-temperature and high-pressure conditions. Here, we develop robust CuNi bimetallic catalysts through direct calcination of dried sol–gel precursors under H2 atmosphere, enabling the complete conversion of furfural to furfuryl alcohol under mild conditions. By adjusting the calcination atmosphere and introducing small amounts of Ni, we achieve the formation of highly dispersed, ultrasmall Cu nanoparticles, resulting in a significant enhancement of the catalytic activity. The optimized 0.5%Ni-10%Cu/SiO2-CA(H2) catalyst demonstrates superior catalytic performance, achieving 99.4% of furfural conversion and 99.9% of furfuryl alcohol selectivity, respectively, at 55 °C under 2 MPa H2, outperforming previously reported Cu-based catalysts. The excellent performance of CuNi bimetallic catalysts can be attributed to the highly dispersed Cu nanoparticles and the synergistic effect between Cu and Ni for H2 activation. This research contributes to the rational design of Cu-based catalysts for the selective hydrogenation of furfural.

In Situ UNIversal Orthogonal Network (UNION) Bioink Deposition for Direct Delivery of Corneal Stromal Stem Cells to Corneal Wounds.

The scarcity of human donor corneal graft tissue worldwide available for corneal transplantation necessitates the development of alternative therapeutic strategies for treating patients with corneal blindness. Corneal stromal stem cells (CSSCs) have the potential to address this global shortage by allowing a single donor cornea to treat multiple patients. To directly deliver CSSCs to corneal defects within an engineered biomatrix, we developed a UNIversal Orthogonal Network (UNION) collagen bioink that crosslinks in situ with a bioorthogonal, covalent chemistry. This cell-gel therapy is optically transparent, stable against contraction forces exerted by CSSCs, and permissive to the efficient growth of corneal epithelial cells. Furthermore, CSSCs remain viable within the UNION collagen gel precursor solution under standard storage and transportation conditions. This approach promoted corneal transparency and re-epithelialization in a rabbit anterior lamellar keratoplasty model, indicating that the UNION collagen bioink serves effectively as an in situ -forming, suture-free therapy for delivering CSSCs to corneal wounds. TEASER. Corneal stem cells are delivered within chemically crosslinked collagen as a transparent, regenerative biomaterial therapy.

Anion-intercalation pseudocapacitance in oxygen vacancy-rich spinel-perovskite NiFe2O4-LaFeO3 nanocomposite for high energy density asymmetric supercapacitor application

Oxide nanomaterials have attracted significant attention as energy storage materials. The combination of spinel-perovskite oxides as nanocomposites creates dense oxygen vacancies (VO) at the hetero-interface. VO present in the complex oxides are indispensable for energy conversion applications. Herein, we demonstrated the one pot synthesis of spinel-perovskite NiFe2O4-xLaFeO3 nanocomposite and investigated the phase formation using variable temperature powder X-ray diffraction of the gel precursor. The role of oxygen-vacancy mediated tuneable redox transitions in NiFe2O4-xLaFeO3 nanocomposite has been understood. The anion-intercalation-based pseudocapacitance and the oxygen intercalation have been exploited for high-performance electrochemical energy storage. The NiFe2O4–2LaFeO3 exhibited a high specific capacity of 652 C g−1 at a current density of 2 A g−1. The fabricated NiFe2O4–2LaFeO3||NiCo2O4 asymmetric supercapacitor device (ASC) exhibited excellent cyclability over 20,000 cycles with superior capacity retention and high Coulombic efficiency (92 %) and achieved a high energy density of 42.5 Wh kg−1 at a power density of 1500 W kg−1. The presence of VO and the mixed-valence states of Fe2+/3+ were confirmed by XPS-depth profiling. The tuneable redox transition of Fe2+/3+ and VO contribute to the higher pseudocapacitance response.

Review on the Polymeric and Chelate Gel Precursor for Li-Ion Battery Cathode Material Synthesis.

The rapid design of advanced materials depends on synthesis parameters and design. A wide range of materials can be synthesized using precursor reactions based on chelated gel and organic polymeric gel pathways. The desire to develop high-performance lithium-ion rechargeable batteries has motivated decades of research on the synthesis of battery active material particles with precise control of composition, phase-purity, and morphology. Among the most common methods reported in the literature to prepare precursors for lithium-ion battery active materials, sol-gel is characterized by simplicity, homogeneous mixing, and tuning of the particle shape. The chelate gel and organic polymeric gel precursor-based sol-gel method is efficient to promote desirable reaction conditions. Both precursor routes are commonly used to synthesize lithium-ion battery cathode active materials from raw materials such as inorganic salts in aqueous solutions or organic solvents. The purpose of this review is to discuss synthesis procedure and summarize the progress that has been made in producing crystalline particles of tunable and complex morphologies by sol-gel synthesis that can be used as active materials for lithium-ion batteries.

Electrochemically assisted sol-gel deposition of bioactive gels for biomedical applications

So far, the sol-gel process has been available to prepare precursor gels of bioactive glasses with various compositions. In this report, we described a novel coating method of bioactive gels on a titanium substrate where the sol-gel transition is controlled by applying external electric fields. The application of a constant current of 10 mA/cm2 in an acidic sol containing pre-hydrolyzed tetraethoxysilane, calcium nitrate, and ammonium dihydrogen phosphate led to the deposition of gels on the titanium cathodes due to the generation of OH– by water electrolysis as a catalyst of the sol-gel transition. The obtained gels, which were characterized to be amorphous and consisted of Si, Ca, and P, covered the titanium substrates as a coating. The bioactivity of the gels deposited was confirmed by soaking in a simulated body fluid (SBF) up to 7 days, suggesting that the electrochemically assisted sol-gel process is promising for providing bioactive coatings on metallic implants.Graphical

Aloe vera gel mediated green synthesis of ruthenium nanoparticles and their potential anticancer activity

Metal nanoparticles have a noteworthy future in cancer treatment research because of their smaller size and large active surface area. Though gold, silver, platinum, palladium, copper, zinc, iron and several other metal nanoparticles have been explored for their anticancer potential in different pathways, the main limitation of these particles is their toxicity which may be controlled through their size, surface modification and route of administration. Compared to other metal nanoparticles, ruthenium nanoparticles have high bio compatibility and they exhibit excellent photo-thermal effect. Though there are several reports in the literature on the anticancer potential of ruthenium complexes, ruthenium nanoparticles are not much investigated. In the present work, therefore, an attempt has been made to synthesize ruthenium nanoparticles in an easy and eco-friendly way using Aloe vera gel. Ruthenium chloride was used as a precursor and Aloe vera gel acted both as reducing and capping agent. The synthesized ruthenium nanoparticles were characterized using UV-Visible spectrophotometry, Fourier Transform Infrared Spectroscopy (FT-IR), High Resolution Transmission Electron Microscopy (HRTEM), Powder X-ray Diffraction (PXRD), Dynamic Light Scattering (DLS) and Field Emission Scanning Electron Microscopy (FESEM). The analyses confirmed the formation of nano globules of Aloe vera gel of diameter in the range 90–300 nm with ruthenium nanoparticles of average size 1.5 nm embedded in them. The synthesized Ru nanoparticles embedded in the nano globules of Aloe vera gel (ALV RuNPs) were explored for their anticancer potential in the Dalton's lymphoma ascites (DL) cell line using Trypan Blue assay. The results of the assay showed that the ALV RuNPs can induce concentration dependent cytotoxicity in DL cancer cells. Approximately 40 % cytotoxicity was obtained for concentration range 5–50 mg/mL of the sample while negligible cytotoxicity was observed for healthy PBMC cells. Theoretical study indicates significant interaction between the components present in Aloe vera and Ru-nanoparticles. The results showed that ruthenium nanoparticles can emerge as a promising bio-compatible candidate with the ability to selectively target cancer cells while sparing normal cells.

Kirkendall effect induced the formation of hollow Co2P in Co-N-C for ORR, OER, HER and flexible Zn–Air battery

Enhancing the exposure of active sites and optimizing the electronic structure of the catalysts are indispensable for efficient catalyst design, yet remains challenging in the renewable energy field. Herein, a sequential pyrolyzing and phosphating approach for a well-designed GO/CoTPP gel precursor has been explored to prepare a Co-based carbon catalyst containing single-atom Co-Nx and hollow Co2P active species (Co2P/Co-N-C) for multifunctional electrocatalytic reactions. Kirkendall effect occurring during the template-free one-pot phosphating approach induced the formation of the hollow Co2P structure in the catalyst, simultaneously optimizing the electron structure and allowing the active sites to be exposed to a greater extent. DFT calculations demonstrated that the Co2P and Co-Nx structures enable Co2P/Co-N-C to have a suitable d-band center depending on the electron transfer from Co2P to Co-Nx, which enhances the adsorption of O* and the dissociation of OH* in oxygen electrode reactions, thereby facilitates catalytic reactions. As a result, the Co2P/Co-N-C exhibits excellent trifunctional activity with a half-wave potential of 0.89 V in alkaline for oxygen reduction reaction (ORR), overpotentials of 330 mV for oxygen evolution reaction (OER) and 190 mV for hydrogen evolution reaction (HER), respectively, which are among the best results reported to date for Co-containing carbon-based catalysts. Furthermore, the flexible Zinc-air battery with Co2P/Co-N-C electrodes also demonstrates a high open circuit voltage of 1.35 V, which is applied to build the self-powered device for water splitting continuously. Our work provides a facile strategy to prepare high-performance trifunctional catalysts by morphology/structure control of metal-based NPs on carbon-based materials.

Microfluidic Assembly of Degradable, Stereocomplexed Hydrogel Microparticles.

Hydrogel microparticles (HMPs) have been investigated widely for their use in tissue engineering and drug delivery applications. However, translation of these highly tunable systems has been hindered by covalent cross-linking methods within microparticles. Stereocomplexation, a stereospecific form of physical cross-linking, provides a robust yet degradable alternative for creating translationally relevant HMPs. Herein, 4-arm polyethylene glycol (PEG) stars were used as macromolecular initiators from which oligomeric poly(l-lactic acid) (PLLA) was polymerized with a degree of polymerization (DPn) of 20 on each arm. Similarly, complementary propargyl-containing ABA cross-linkers with enantiomeric poly(d-lactic acid) (PDLA) segments (DPn = 20) on each arm. Droplets of these gel precursors were formed via a microfluidic organic-in-oil-in-water system where microparticles self-assembled via stereocomplexation and were stabilized after precipitation in deionized water. By varying the flow rate of the dispersed phase, well-defined microparticles with diameters of 33.7 ± 0.5, 62.4 ± 0.6, and 105.7 ± 0.8 μm were fabricated. Gelation due to stereocomplexation was confirmed via wide-angle X-ray scattering in which HMPs exhibited the signature diffraction pattern of stereocomplexed PLA at 2θ = 12.2, 21.2, 24.2°. Differential scanning calorimetry also confirmed stereocomplexation by the appearance of a crystallization exotherm (Tc = 37 °C) and a high-temperature endotherm (Tm = 159 °C) that does not appear in the homocrystallization of PLLA or the hydrogel precursors. Additionally, the propargyl handle present on the cross-linker allows for pre- or post-assembly thiol-yne "click" functionalization as demonstrated by the addition of thiol-containing fluorophores to the HMPs.

Highly crystalline yttria‐stabilized zirconia and titania thin films on plastic substrates via sol‐gel transfer process

AbstractWe prepared yttria‐stabilized zirconia (YSZ) and titania crystalline thin films on polycarbonate (PC) substrates by the sol‐gel transfer technique that we have developed recently. Precursor gel films were deposited by spin‐coating on a polyimide/polyvinylpyrrolidone mixture layer on Si(100) substrates, and then were calcined at 600°C. The spin‐coating and the calcination were cycled, followed by final firing at 600–1000°C, to obtain 140–190 nm thick, YSZ and titania crystalline thin films. The film densification progressed as the final firing temperature increased, where the porosity calculated from the refractive index decreased down to a few percent. The film thus obtained was heated at 190°C on a hot plate, and a PC substrate was pressed on the film to transfer it to the PC substrate. The transferability quantified by image analysis of the film area was found to be significantly different between the YSZ and titania films. In the case of YSZ films, the area of silicon that was fractured and adhered to the transferred film increased significantly with increasing firing temperature, leading to a decrease down to 0% in the fraction of the successful transfer area without such a damage. On the other hand, the fraction of the successful transfer area remained around 90% irrespective of the firing temperature for the titania films. The surface of the titania films that were fired at 800–1000°C and transferred to PC substrates had voids of several tens nm scale, which may have been formed during anatase‐to‐rutile phase transformation. We thought that the reduced titania/Si(100) contact area due to such void formation facilitated the delamination of the titania films from Si(100) substrates. High temperature firing, which promotes crystallization and densification of films, thus affects differently the film transferability to plastic substrates, depending on the type of films. The work also suggested possible use of titania films as release‐assisting layers.

Nanocellulose membrane with double-salt deep eutectic solvent for efficient carbon capture

Membrane-based gas separation technology is becoming increasingly attractive as a feasible alternative for carbon capture to alleviate global warming. Here, a double-salt deep eutectic solvent (DES) composed of organic salt (choline chloride) and inorganic salt (ZnCl2) is designed. The as-prepared DES exhibits a superb affinity and compatibility with nanocellulose because of the interactions between salt ions and cellulose carboxyl/hydroxyl groups. Through a solvent impregnation process, the DES was integrated into the nanocellulose gel precursor and used as a facilitated transport agent to form the functionalized nanocellulose membrane. The DES is tightly attached to the cellulose fibers with a high uniformity in the membrane matrix. Gas separation tests demonstrated that the DES@nanocellulose membranes presented a maximum CO2 permeability of 155.8 Barrer, with CO2/N2 and CO2/CH4 ideal selectivities of 43.6 and 48.4, respectively. Mixed gas separation tests were performed and the optimal membrane exhibited separation factors of 48.1 and 52.3 for CO2/N2 and CO2/CH4, respectively. The membranes provide a high solubility for CO2 due to the presence of abundant zinc ions, choline cations and carboxyl groups in the network, which can establish reversible coordination with CO2 and promote CO2 transport.

Interzeolite Transformation from FAU-to-EDI Type of Zeolite.

This study reports for the first time the transformation of the pre-made FAU type of zeolite to the EDI type of zeolite. The concentration of the KOH solution controls this interzeolite transformation, which unusually occurs at both room temperature and under hydrothermal conditions. The transformation involves the amorphization and partial dissolution of the parent FAU phase, followed by the crystallization of EDI zeolite. At room temperature, the transformation (11-35 days) provides access to well-shaped nano-sized crystals and hollow hierarchical particles while the hydrothermal synthesis results in faster crystallization (6-27 h). These findings reveal an example of an interzeolite transformation to a potassium zeolite that lacks common composite building units with the parent zeolite phase. Finally, this work also demonstrates the first room-temperature synthesis of EDI zeolite from a gel precursor.

Structural design and antibacterial properties of porous SiO2/ZnO/Cu2O composites

In this study, the main antibacterial agent employed was nano-ZnO/Cu2O composite powder. The nano-ZnO/Cu2O composite powder was thoroughly dispersed within the gel precursor and subsequently utilized as a carrier for the preparation of porous SiO2 via sol–gel method. Finally, porous SiO2/ZnO/Cu2O composites were obtained. Through the characterization of the phase and structure of the composites, it can be found that nano-ZnO/Cu2O is physically embedded in the porous SiO2 skeleton and fully combined with the porous SiO2. Finally, porous SiO2/ZnO/Cu2O composites were successfully synthesized. The phase and structure of the composites were thoroughly characterized, revealing that nano-ZnO/Cu2O was physically embedded within the porous SiO2 framework and exhibits excellent integration with the porous SiO2 matrix. Compared to single-component nano-ZnO/Cu2O, the composite exhibits significantly enhanced specific surface area and improved pore properties, thereby leading to an enhancement in photocatalytic performance. Furthermore, the antibacterial performance test of the composites clearly demonstrates a remarkable 100% antibacterial rate. Porous SiO2/ZnO/Cu2O composites offer a novel avenue for enhancing the antibacterial properties of ZnO and Cu2O.

Photonic curing for innovative fabrication of flexible metal oxide optoelectronics

Flexible optoelectronics, based on non-planar substrates, hold promise for diverse applications such as wearables, health monitors, and displays due to their cost-effective manufacturing methods. Despite the superior properties of metal oxides, the challenge of processing them at high temperatures incompatible with plastic substrates necessitates innovative annealing approaches. Photonic curing, which delivers microsecond to millisecond broadband (200–1500 nm) light pulses on a sample, emerges as a viable solution. Depending on the optical properties, the targeted film absorbs the radiant energy resulting in rapid heating while the transparent substrate absorbs a minimal amount of light and remains at ambient temperature. The light intensity can be high, but since the light pulse is short, the total energy absorbed by the sample remains low and will not damage the plastic substrate. This perspective explores the innovative application of photonic curing to fabricate flexible metal oxide optoelectronics, including thin-film transistors, metal–insulator–metal devices, solar cells, transparent conductors, and Li batteries, emphasizing the conversion of sol–gel precursors to metal oxides. However, this technique was initially developed for sintering metal nanoparticles to conductive patterns and poses intriguing challenges in explaining its mechanism for metal oxide conversion, especially considering the limited absorption of visible light by most sol–gel precursors. The review delves into UV-induced photochemistry, common flexible metal-oxide optoelectronic components, and non-intuitive distinctions between photonic curing and thermal annealing. By elucidating the distinctive role of photonic curing in overcoming temperature-related challenges and advancing the fabrication of flexible metal oxide optoelectronics, this perspective offers valuable insights that could shape the future of flexible optoelectronics.

Synthesis and characterization of foams generated via gel state frontal polymerization

AbstractIn conventional foams, anisotropy within the microcellular structure can only be achieved through confinement in one or more directions during the foaming process. Herein, we present a novel, versatile, and energy efficient method to create unique high‐performance foams where the anisotropy of the microcellular and the microcellular structure itself is not dictated by external confinement during the foaming process. To generate such foams, an initial crosslinked gel is first created where the crosslink density of the gel can be tuned by UV intensity and cure time. Next, the gel can be foamed while simultaneously creating a second network via radically induced cationic frontal polymerization (RICFP). In this case, the anisotropy in the foam is dictated by propagation front during the RICFP and the microcellular morphology and cell surface area are dictated by the crosslink density of the gel. These two unique qualities lead to rigid foams that can be generated from a gel without the need for confinement where the microcellular size and shape can be tuned by the crosslink density of the gel precursor. A one‐pot liquid system composed of miscible epoxies, acrylates, and chemical blowing agents (CBAs), allows for control over the foam physical, mechanical, and thermal properties with glass transition temperatures ranging from 74.7 to 125.8°C. Additionally, by patterning the crosslink density of the initial gel through controlled exposure of UV, complex microcellular structures can be formed that are not possible in conventional foaming processes. This positions gel frontal polymerization and foaming as an advanced technique to produce high performing anisotropic foams with a wide array of tunable physical, mechanical, and thermal properties.

Enhanced dimensional stability of straw-based biocomposites modified with UV light-cured coatings

This study demonstrated an effective method to enhance the dimensional stability of straw-based biocomposites with modified lignosulfonate as a binder. The ultraviolet (UV) light-curable nanosol was prepared by adding 3-(trimethoxysilyl)propyl methacrylate (MEMO) as sol–gel precursor into polyvinyl alcohol (PVA) solution. The MEMO/PVA coatings were generated using 2-hydroxy-2-methyl-1-phenylpropan-1-one (Darocur 1173) as radical photo-initiator and chitosan (CS) as additive, on straw-based biocomposites via UV-curing process. The effects of the crucial steps, such as the UV-curing process, hydrolysis time, Darocur 1173 dosage, and CS dosage on the dimensional stability of straw-based biocomposites, were evaluated. The optimum preparation parameters, obtained using the Box–Behnken design, were 31.9 min hydrolysis time, 4.5% Darocur 1173 dosage, and 2.7% CS dosage. Moisture resistance of minimum TS of CS-MEMO/PVA-coated straw-based biocomposites resulted in ~23.1% reduction in dimensional stability without significant decline in the mechanical properties when compared with those without UV curing. Moreover, the glossy spherical particles underwent arrangement in a fish-scale shape with scales closely linked with each other and no agglomeration occurred in CS-MEMO/PVA hybrid film. The CS promoted the cross-linking of MEMO/PVA coating on the biocomposite surface. The resulting biocomposites can be directly applied to public humid-environment applications such as bath furniture and bathroom partitions.

Design Synthesis of Low-Silica SAPO-34 Nanocrystals by Constructing Isomorphous Core-Shell Structure: An Effective Catalyst for Improving Catalytic Performances in Methanol-to-Olefins Reaction.

It is well known that low-silica SAPO-34, with an extra porosity (meso- and/or macropores) system, affords excellent catalytic performance in the methanol-to-olefins (MTO) reaction, while the direct synthesis of low-silica SAPO-34 with a hierarchical structure is difficult to achieve, principally because the crystal impurities are usually formed under a low silica content in a gel precursor. Herein, low-silica SAPO-34 nanocrystals were successfully fabricated for the first time by constructing an isomorphous core-shell structure in an epitaxial growth manner. In which, low-silica, ultrasmall nanosquare-shaped SAPO-34 crystals with the same growth orientation along the (100) crystal plane compactly grow on the monocrystal SAPO-34 cores. Crucially, the external surface acid properties of the core SAPO-34 with the Si-rich outer layer are effectively modified by the low-silica SAPO-34 shell. Furthermore, the growth process and Si-substitution mechanism of the shell zeolite were comprehensively investigated. It was found that with the prolonged crystallization time, more and more coordinated Si(4Al) and Si(3Al) structures via two substitution mechanisms (SM2 and SM3) are generated in the nanocrystalline SAPO-34 shell, which endow moderate acidity of the core-shell SAPO-34. Compared to the uncoated SAPO-34, the core-shell SAPO-34 performs a longer lifespan and a higher average selectivity of light olefins (ethylene plus propylene) when applied to the MTO reaction, which is attributed to the positive effects of the luxuriant interstitial pores offering a fast diffusion channel and the moderate acid density depressing the hydrogen transfer reaction of light olefins. This work provides new insights into the fabrication of low-silica SAPO-34 nanocrystals, which are based on the rational design of the isomorphous core-shell zeolite.

Gel‐Derived Amorphous Precursor Enables Homogeneous Pure‐Phase α‐FAPbI3 Films for Efficient and Stable Perovskite Solar Cells

AbstractPure‐phase α‐formamidinium lead iodide (α‐FAPbI3) perovskite solar cells (PSCs) possess potential high efficiency because of suitable bandgap. However, achieving high‐quality α‐FAPbI3 films during the spin‐coating process is challenging without anti‐solvent extraction, due to the spontaneous formation of the more stable δ‐FAPbI3 phase and the complexity of multi‐component perovskite precursor solutions. Here a gel precursor with an amorphous structure to eliminate the need for anti‐solvent extraction in achieving the homogeneous and highly oriented pure‐phase α‐FAPbI3 is devised films. The incorporation of N,N′‐dimethylpropyleneurea, and alkylammonium chloride results in extended iodoplumbate clusters in the perovskite precursor solution. In situ, spectroscopic analysis reveals that the emergence of the stable amorphous gel precursor during the initial solidification stage ensures a uniform solute distribution. This effectively prevents preferentially oriented growth in the crystal phase precursor, leading to a significant enhancement in film homogeneity. As a result, power conversion efficiencies of 24.17% for the PSC, and 19.3% for the module are achieved, along with superior operational stability, retaining 96.1% of their initial efficiency after 850 h at the maximum power point tracking. These demonstrate the best performance for the reported pure‐phase α‐FAPbI3 PSCs without anti‐solvent extraction, showing great promise for scalable manufacture.