Spherical Porous Structure Research Articles

Regulation of receptor function in NiCo2O4-SnO2 heterojunction for H2S detection at room temperature

In recent years, the World Health Organization has increasingly emphasized air quality in production environments, leading to heightened societal demands for monitoring of pollutant gases at room temperature. Traditional semiconductor gas-sensitive materials, such as tin oxide (SnO2), have their gas-sensing performance largely limited by their receptor functions, resulting in common issues like low response and poor recovery at room temperature. Spinel-type bimetallic oxides, such as nickel cobaltate (NiCo2O4), offer a unique solution due to their rich adsorption sites on the surface, which provide distinctive receptor functions for detecting toxic gases at room temperature. Herein, NiCo2O4 is synthesized via a one-step hydrothermal method, with a porous spherical cluster structure, and combined with SnO2 to form a heterojunction. The NiCo2O4-SnO2 heterojunction film gas sensor exhibits excellent gas-sensing performance for H2S at room temperature, including high response, short response time, good repeatability, and selectivity. Additionally, the unique receptor functions of the NiCo2O4 were analyzed through first-principles calculations, revealing a semiconductor p-n conversion phenomenon in the presence of H2S gas. The composite also demonstrates a conversion from p-n heterojunction to n-n homojunction during the sensing process, enhancing its gas-sensing performance. This work not only addresses the receptor function limitations of traditional gas-sensitive semiconductor but also provides a feasible approach for controlling carrier types in semiconductors.

Sustained-release effect of eggshell powder microcapsules on lavender essential oil

Eggshells are rich in Ca2+ and organic compounds, which can be taken as coupling agents for sustained-release materials. Essential oils are widely applied due to their excellent volatility, but poor sustained-release stability has limited their development. The study aimed to develop a novel eggshell powder (EP) sustained-release microcapsule, providing a new approach to protect the active ingredients of Lavender essential oil (LEO), and investigated the reasons for EP to regulate protein-polysaccharide microcapsule structure. Experimental results showed when the addition ratio of EP and Whey protein (WPI) was 1: 3, the dosage of LEO was 25%, the microcapsule displayed smooth and porous spherical structure. XRD and FT-IR indicated that a dense and orderly network structure was formed via the cross-linking reaction between eggshell powder and wall materials, which induced protein and polysaccharide to form special spherical hollow sustained-release shell structure through the calcium bridge (-COO-Ca-COO-), then achieved the sustained-release effect on LEO.

Combined steam and CO2 reforming of methane over Ni-based catalysts with spherical porous structure

Combined steam and dry reforming of methane (CSDRM) is expected to be promising when considered as a new alternative feedstock for F-T synthesis because it can produce high-quality syngas without carbon deposition. In this study, the support particle sizes were varied independently to assess their influence on the performance of the metallic Ni. The catalytic activity is most influenced by nickel particle size and distribution, and it has also been investigated for its significant role in the metal-support interaction. To perform CSDRM, the Ni-based catalyst was prepared by impregnation method on a spherical nano-silica support prepared by sol–gel method. The size of the spherical silica nanoparticles (40–300 nm) was controlled by varying the ethanol molar concentration; the spherical particles showed high performance on a uniform and evenly drawn support. In the 44 nm spherical silica catalyst, it was confirmed that the maximum dispersion increased to 21 % and the reducibility increased to 36 %. For stable synthesis gas production, various feed gas ratios (0.7:1.3:1.7) were established and the respective feed gas components (CH4, CO2 and steam) and reactions were investigated. Also, with the increase in the concentration of steam in the feed gas ratio, there was a significant increase in CO production. This trend was attributed to competing reactions occurring due to the side reactions (WGS↔RWGS; CO+H2O↔CO2 + H2) and was investigated with equilibrium constant values using thermodynamic equilibrium plot data. From the experimental results obtained, the catalyst showed high performance on a stable support and produced a stable H2/CO ratio of 2 for 100 h, without side reactions, at the feed gas ratio (CH4:CO2:H2O = 1:0.6:0.85).

In vitro and in vivo degradation profile, biocompatibility of poly-L-lactic acid porous microspheres

The objective of this study is to evaluate the in vitro and in vivo degradation profile and biocompatibility of poly-L-lactic acid (PLLA) porous microspheres (PMs) for their potential application as injectable microcarrier or micro-scaffolds materials in the research and clinical use of craniofacial cartilage repair. In this study, PLLA PMs prepared exhibited spherical shape and uniform surface pores followed by 24-week evaluations for degradation behavior and biocompatibility. In vitro degradation analysis encompassed morphological examination, pH monitoring, molecular weight analysis, thermodynamic assessment, and chemical structure analysis. After 12 weeks of in vitro degradation, PMs maintained a regular porous spherical structure. Molecular weight and glass transition temperature of PLLA PMs decreased over time, accompanying with an initial increase and subsequent decrease in crystallinity. Enzymatic degradation caused morphological changes and accelerated degradation in the in vitro studies. Finally, in vivo evaluations involved subcutaneous implantation of PLLA PMs in rats, demonstrating biocompatibility by enhancing type I and type III collagen regeneration as observed in histological analysis. The results demonstrated that PLLA PMs were able to maintain their spherical structure for 12 weeks, promoting the generation of collagen at the implantation site, meeting the time requirements for craniofacial cartilage repair.

Assembly of Amorphizing Porous Bimetallic Metal‐Organic Frameworks Spheres with Zn─O─Fe Cluster and Coordination Deficiency via Ligand Competition for Efficient Electro‐Fenton Catalysis

AbstractElectro‐Fenton process stands out as a highly promising approach for generating reactive oxygen‐containing radicals to address the escalating issue of environmental pollution. However, the long‐term goal of application necessitates ongoing pursuit of high‐quality catalysts with both sufficient activity and stability. Herein, a general route is reported for large‐scale synthesis of amorphizing porous bimetallic metal‐organic framework (MOF) spheres with Zn─O─Fe structure and coordination deficiency through facile and low‐cost synthesis of ligand competition. Assisted by a coordination modulator, deprotonation of terephthalic acid is accelerated and rapid synthesis of amorphous bimetallic MOF spheres is successfully achieved at room temperature. As inactive metal Zn is introduced into metal clusters of MOFs, the cycling efficiency of Fe3+/Fe2+ is improved and a secondary building unit of Zn─O─Fe is constructed, greatly accelerating electron conduction rate. Compared to crystalline spindle cMIL‐88B(Fe2Zn) by traditional solvothermal route, amorphous aMIL‐88B(Fe2Zn) has a unique spherical porous structure with larger surface area, higher conductivity, and more exposed active sites. Endowed with unique textural and surface chemistry, aMIL‐88B(Fe2Zn) exhibits superior catalytic activity in the degradation of refractory organic pollutants. The progress offers a feasible way to rational design of iron‐based hybrid MOF materials with tunable structures and enhance properties for various applications.

Study on the Preparation of Silicon-Based Anode Materials with Porous Structure by Etching

Silicon has the advantages of high specific capacity (4200 mAh/g), low lithium potential and abundant reserves, and is considered to be one of the most suitable materials for replacing graphite negative electrode. However, the commercial silicon particle size is too large to be used directly as an electrode material, and the silicon material will undergo huge volume expansion during the lithium insertion process, resulting in the fragmentation of the active substance falling off from the fluid collector, resulting in a sharp decline in battery capacity. This defect seriously affects the commercial application of silicon-based anode materials. In this paper, a kind of silicon anode material with porous structure is designed for the defect of silicon anode material. The aluminum-silicon alloy prepared by atomization method presents a three-dimensional porous spherical structure after etching, and the abundant holes reserve space for the volume expansion during the process of lithium silicon embedding and improve the transmission rate of lithium ions. It was found that when the silicon content was 12%, the reversible specific capacity of the material was 1269 mAh/g at 4000 mA/g current density, and the capacity retention rate of 100 cycles relative to the fourth cycle was 59.5%. Compared with ball-ground silicon, the capacity retention rate is increased by 25.7%. Therefore, this paper provides a new idea for the design of porous silicon-based anode materials.

Biomass-derived N–P double-doped porous carbon spheres and their lithium storage mechanism

Biomass-derived carbon materials are widely studied and used in energy storage applications. Unfortunately, the disadvantages such as poor capacity and rate performance limit their development. Heteroatom doping can effectively improve the electrochemical properties of biomass-derived carbon materials. In this work, we designed and prepared environmentally friendly and cost-effective biomass (lotus root)-derived nitrogen-phosphorus (N–P) double-doped porous carbon spheres. When used as an anode material for a lithium-ion battery, the porous carbon spheres exhibited excellent stability performance (a reversible capacity of 739.6 mAh g−1 after 100 cycles at 0.1 A g−1 and 599.16 mAh g−1 after 215 cycles at 0.5 A g−1, respectively) and superior rate performance (a capacity of 187.22 mAh g−1 at 10 A g−1) due to the synergy of the heteroatomic doping and the layered porous spherical structure. The novel biomass-derived material based on N–P double-doped porous carbon spheres can serve as a cost-effective option for anode materials of lithium-ion batteries. Besides, an “adsorption-pore filling/intercalation” hybrid mechanism is proposed to understand the possible principle for superior lithium storage performance based on CV, ex-situ Raman and XRD results.

Doping Ni into CoB achieves surface reconstruction to promote efficient electrocatalytic hydrogen evolution reaction

The effective advancement of skilled transition metal electrocatalysts is crucial for promoting the hydrogen evolution reaction (HER) in the process of water splitting. In this context, the integration of nickel (Ni) transition metal atoms into cobalt boride (CoB) is achieved through an electrochemical deposition approach, yielding a remarkably active electrocatalyst termed Ni@CoB for HER. At 10 mA cm−2, the HER overpotential is 63 mV with a Tafel slope of 64.73 mV dec-1. After 50 h of stability testing, there was no significant current decay observed. By employing material characterization techniques and DFT calculations, it has been shown that the incorporation of Ni leads to a surface reconstruction of CoB, thereby decreasing surface aggregation. The catalyst exhibits a uniform spherical porous structure, facilitating enhanced electron transfer. The doped Ni atoms form a bimetallic synergistic effect with Co atoms, not only increasing the stability of interatomic covalent bonds but also enhancing reaction kinetics. This study illuminates the influence of incorporating transition metal atoms into CoB on the activity of HER, presenting a promising strategy for designing high-performance catalysts for alkaline hydrogen evolution.

Electrostatic Spraying Microspheres of Nano Boron and Its Constant-Volume Combustion with Potassium Nitrate

ABSTRACT The nanometer boron (nB) powders have become the most promising high-energy additive in the field of fuel-rich solid propellants due to their extremely high gravimetric and volumetric calorific value. However, further applications are limited by its disadvantages such as easy agglomeration, easy oxidation, high ignition temperature, and incomplete energy release. Herein, nB powders were pre-agglomerated into microspheres by electrostatic spray method using fluoropolymer (F2602) as binders. The morphology and structure of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET). Results showed that the pre-agglomerated nB microspheres had good dispersion, high sphericity, and no surface oxide. The thermal performance and combustion performance of the samples were characterized by a synchronous thermal analyzer and combustion pressure test device. Results showed that the nB microspheres had the highest oxidation weight gain within 1000°C and lowest activation energy compared to the same scale micron boron. In addition, the microspheres significantly shorten the combustion time and improve the combustion efficiency.The pressurization rate of nB microspheres is 4.12 times that of micron boron powders and 2.85 times that of nB powders. These excellent properties may be related to its unique spherical porous structure. Therefore, the preparation of nB microspheres with controllable structure by electrostatic spraying has a good application prospect.

Ultrasensitive detection and efficient removal of mercury ions based on covalent organic framework spheres with double active sites

In present work, a new spherical covalent organic framework (TFPB−APTU COF) with good photoelectric property and double active sites (secondary amine (−NH−) group and sulfur (S) atom) was prepared for ultrasensitive detection and efficient removal of mercury ions (Hg2+). The –NH− group and S atom can capture free Hg2+ by coordination and chelation interaction, and the related steric hindrance effect reduces the photocurrent signal of the TFPB−APTU COF, resulting in the highly sensitive photoelectrochemical analysis of Hg2+ with a wide linear response range (0.01−100000 nM) and low detection limit (0.006 nM). On the other hand, the developed TFPB−APTU COF has large removal capacity (2692 mg g−1), good regeneration capability, and high removal speed for Hg2+ removal based on the double active sites (−NH− group and S atom), large specific surface area and porous spherical structure. The developed TFPB−APTU COF spheres show great potential in monitoring and treatment of environmental pollution of Hg2+.

Injectable hydrogel microspheres experimental research for the treatment of osteoarthritis

To prepare a novel hyaluronic acid methacrylate (HAMA) hydrogel microspheres loaded polyhedral oligomeric silsesquioxane-diclofenac sodium (POSS-DS) patricles, then investigate its physicochemical characteristics and in vitro and in vivo biological properties. Using sulfhydryl POSS (POSS-SH) as a nano-construction platform, polyethylene glycol and DS were chemically linked through the "click chemistry" method to construct functional nanoparticle POSS-DS. The composition was analyzed by nuclear magnetic resonance spectroscopy and the morphology was characterized by transmission electron microscopy. In order to achieve drug sustained release, POSS-DS was encapsulated in HAMA, and hybrid hydrogel microspheres were prepared by microfluidic technology, namely HAMA@POSS-DS. The morphology of the hybrid hydrogel microspheres was characterized by optical microscope and scanning electron microscope. The in vitro degradation and drug release efficiency were observed. Cell counting kit 8 (CCK-8) and live/dead staining were used to detect the effect on chondrocyte proliferation. Moreover, a chondrocyte inflammation model was constructed and cultured with HAMA@POSS-DS. The relevant inflammatory indicators, including collagen type Ⅱ, aggrecan (AGG), matrix metalloproteinase 13 (MMP-13), recombinant A disintegrin and metalloproteinase with thrombospondin 5 (Adamts5), and recombinant tachykinin precursor 1 (TAC1) were detected by immunofluorescence staining and real-time fluorescence quantitative PCR, with normal cultured chondrocytes and the chondrocyte inflammation model without treatment as control group and blank group respectively to further evaluate their anti-inflammatory activity. Finally, by constructing a rat model of knee osteoarthritis, the effectiveness of HAMA@POSS-DS on osteoarthritis was evaluated by X-ray film and Micro-CT examination. The overall particle size of POSS-DS nanoparticles was uniform with a diameter of about 100 nm. HAMA@POSS-DS hydrogel microspheres were opaque spheres with a diameter of about 100 μm and a spherical porous structure. The degradation period was 9 weeks, during which the loaded POSS-DS nanoparticles were slowly released. CCK-8 and live/dead staining showed no obvious cytotoxicity at HAMA@POSS-DS, and POSS-DS released by HAMA@POSS-DS significantly promoted cell proliferation (P<0.05). In the chondrocyte anti-inflammatory experiment, the relative expression of collagen type Ⅱ mRNA in HAMA@POSS-DS group was significantly higher than that in control group and blank group (P<0.05). The relative expression level of AGG mRNA was significantly higher than that of blank group (P<0.05). The relative expressions of MMP-13, Adamts5, and TAC1 mRNA in HAMA@POSS-DS group were significantly lower than those in blank group (P<0.05). In vivo experiments showed that the joint space width decreased after operation in rats with osteoarthritis, but HAMA@POSS-DS delayed the process of joint space narrowing and significantly improved the periarticular osteophytosis (P<0.05). HAMA@POSS-DS can effectively regulate the local inflammatory microenvironment and significantly promote chondrocyte proliferation, which is conducive to promoting cartilage regeneration and repair in osteoarthritis.

Spherical porous structures for axial compression

Porous structures have attracted much attention because of the advantages of lightweight and strong energy absorption efficiency. This work proposes a spherical porous structure (SPS) and a square porous structure (SQPS), and the SPS sample is manufactured by selective laser sintering (SLS) technique with the material nylon 11. Their axial compression results of experiment and simulation show that the compressive strength of hollow cylinders is greater than that of porous spheres, and porous spheres are always crushed during compression. SPS exhibits the rapid collapse characteristics of porous spheres layer by layer, and it shows four sharp valley forces and significant negative stiffness characteristic. In addition, the specific energy absorption (SEA) value of SPS is higher than that of SQPS 30.84%. The compression capacity of porous spheres is stronger than that of porous cubes. This study furtherly discuss the mechanical behavior of SPS with different structural parameters. The negative stiffness characteristic, energy absorption efficiency and deformation mode of SPS depends on the strength combination of porous spheres and hollow cylinders, and smaller overall cell size, more cell layers, and thicker cells contribute to improving the anti-compression properties of SPS. The SEA values of SPS- T1.6 and SPS- F7 are 12.52% and 12.16% higher than that of SPS. In summary, SPS shows novel mechanical properties, providing a reference for the design of new energy absorbers.

Cooperative regulation of hard template and emulsion self-assembly to the synthesis of N/O co-doped mesoporous hollow carbon nanospheres for supercapacitors

Hollow carbon nanospheres have attracted more and more attention as supercapacitor materials due to their excellent electrical conductivity, high theoretical surface area, high accumulation and rapid ion transfer and diffusion. In this work, we employed the Stöber method to create silica as a template, and then applied self-assembly and dopamine polymerization on the surface of the template to form SiO2@TMB-F127-PDA micelles. Then the nitrogen-doped mesoporous hollow carbon nanospheres (N-MHCNs) were prepared by carbonization and etching on the formed carbon precursors. The effect of dopamine amount on the structure and properties of N-MHCNs was systematically studied. Microstructural characterization results reveal that the morphology of N-MHCNs can be changed from sheet to sphere, and the particle size of N-MHCNs can be 33.8–225.7 nm, the specific surface area is distributed in the range of 175.9–430.1 m2 g−1. Due to the N,O heteroatomic co-doping and Porous spherical structure (with a small particle size of 33 nm, and a large specific surface area of 430.1 m2 g−1), typical sample N-MHCNS-2 shows excellent electrochemical performance in supercapacitors. And it has the highest specific capacitance (241 F g−1) at 0.5 A g−1 current density, excellent rate performance (capacity retention rate of 79 % when current density increases from 0.5 to 10 A g−1) and good cycling ability (capacity retention rate of 90.4 % after 3000 cycles), indicating that it shows great potential in energy storage. This approach provides new opportunities for the controllable synthesis of hollow mesoporous nanospheres and it can be extended to other systems such as hollow metals, metal oxide nanomaterials and carbon-based hybrids.

3D culture of fibroblasts and neuronal cells on microfabricated free-floating carriers

3D cell culture is a relatively recent trend in biomedical research for artificially mimicking in vivo environment and providing three dimensions for the cells to grow in vitro, particularly with regard to surface-adherent mammalian cells. Different cells and research objectives require different culture conditions which has led to an increase in the diversity of 3D cell culture models. In this study, we show two independent on-carrier 3D cell culture models aimed at two different potential applications. Firstly, micron-scale porous spherical structures fabricated from poly (lactic-co-glycolic acid) or PLGA are used as 3D cell carriers so that the cells do not lose their physiologically relevant spherical shape. Secondly, millimetre-scale silk fibroin structures fabricated by 3D inkjet bioprinting are used as 3D cell carriers to demonstrate cell growth patterning in 3D for use in applications which require directed cell growth. The L929 fibroblasts demonstrated excellent adherence, cell-division and proliferation on the PLGA carriers, while the PC12 neuronal cells showed excellent adherence, proliferation and spread on the fibroin carriers without any evidence of cytotoxicity from the carriers. The present study thus proposes two models for 3D cell culture and demonstrates, firstly, that easily fabricable porous PLGA structures can act as excellent cell carriers for aiding cells easily retain their physiologically relevant 3D spherical shape in vitro, and secondly, that 3D inkjet printed silk fibroin structures can act as geometrically-shaped carriers for 3D cell patterning or directed cell growth in vitro. While the ‘fibroblasts on PLGA carriers’ model will help achieve more accurate results than the conventional 2D culture in cell research, such as drug discovery, and cell proliferation for adoptive cell transfer, such as stem cell therapy, the ‘neuronal cells on silk fibroin carriers’ model will help in research requiring patterned cell growth, such as treatment of neuropathies.

Crystallization kinetics and crystallization process of pseudoboehmite from ammonium aluminum sulfate solution

In this work, the crystallization kinetics of pseudoboehmite was studied by intermittent crystallization method. The kinetic model of pseudoboehmite process was established based on particle number equilibrium. The results show that the nucleation is mainly caused by crystal collision, the main speed control step is diffusion process, and the enlargement of crystals mainly originates from the growth. Reducing the temperature of system can obtain pseudoboehmite crystals which have larger particle size and more uniform particle size distribution. Two parallel octahedral units connected by hydroxyl groups are preferentially stacked along the (020) crystal plane. Excessive interlayer water molecules between (020) crystal planes lead to an increase in the interlayer distance. The increased distance between (020) layers will weaken the hydrogen bond between layers, as well as the electrostatic forces and van der Waals forces, resulting in the formation of folded layers with holes. Finally, the irregularly sheets of pseudoboehmite are stacked to form porous spherical structures.

Adsorption of RhB dye on soy protein isolate-based double network spheres: Compromise between the removal efficiency and the mechanical strength

Soy protein isolate-based double network spheres (SPIDNS) were designed and adopted for the first time for Rhodamine B (RhB) dye removal from wastewater. The SPIDNS were prepared through the aziridine crosslinker and the Ca2+ ionic double crosslinking method with major crosslinking agents of soy protein isolate and sodium alginate, in which aziridine crosslinker was also employed as a modifier to regulate the mechanical strength. The physicochemical properties of the materials were explored by numerous technologies, including SEM NMR, FT-IR, and XPS, which confirmed the chemical and physical crosslinked networks of SPIDNS being established after aziridine crosslinker and Ca2+ ionic crosslinking process. Adsorption performances for RhB removal were investigated under various conditions by using SPIDNS with different dosages of aziridine crosslinker for 0%, 1.8%, 3.6%, 5.3%, 6.9%, and 8.5%. Experimental results demonstrated that the mechanical stability of the adsorbent was enhanced with increasing the amount of aziridine crosslinker from 0% to 8.5%; whereas, the adsorption capacity decreased from 190 to 120 mg/g. Therefore, a compromise between the removal efficiency and the mechanical strength should be taken into account. Studies of adsorption kinetics, isotherms, and thermodynamics displayed that the spontaneous RhB adsorption on SPIDNS was well described by a pseudo-second-order kinetic model and Langmuir isotherm model with monolayer adsorption behavior, for which both the correlation coefficients R2 were higher than 0.99. Moreover, electrostatic interactions between the positively charged RhB molecules and the negatively charged SPIDNS were proposed as the principal adsorption mechanism, which was confirmed by Zeta potential analysis. The good mechanical stability and spherical porous structure make the SPIDNS with reliability and potential for practical application.

Modified preparation of Si@C@TiO2 porous microspheres as anodes for high-performance lithium-ion batteries.

Microscale porous silicon materials have shown great application potential as anodes for next-generation lithium-ion batteries (LIBs); however, they face significant challenges, including mechanical structure instability, low intrinsic conductivity, and uncontrollable processing. In this study, a modified etching strategy combined with a facile sol-gel method is demonstrated to prepare microscale porous Si microspheres encapsulated by an inner amorphous carbon shell (≈10 nm) and an outer rigid anatase titanium oxide (TiO2) shell (≈20 nm) (PSi@C@TiO2), with the intact porous framework and core-shell-shell spherical structure. The interconnected pores can sufficiently accommodate the expansion of the Si core during lithiation. Moreover, the double shells can not only enhance the kinetic behavior of the PSi@C@TiO2 microspheres, but can act as a compact fence to force the Si core to expand toward the internal pores during lithiation, ensuring the integrity of the porous spherical structure. As a result, the PSi@C@TiO2 anodes show greatly superior high specific capacity, excellent rate capability, stable solid-electrolyte interphase (SEI) films and steady mechanical structure. It delivers a high reversible capacity of 1004 mA h g-1 after 250 cycles at 0.5 A g-1. This study provides a modified method to prepare microscale porous Si anodes with a stable mechanical structure and long cycle life for LIBs.

Fabrication of ceramic sealing coatings for shell bionic structures and their failure mechanism during thermal cycling

The porous ceramic coating as a "brick" layer sprayed by air plasma spraying(APS) and MK resin as a "mud" layer prepared by a high viscosity spray gun were characterized and tested. Three specifications of the "brick-mud" layered ceramic sealing coating were fabricated through the cyclic and orderly deposition of the "brick" layer and "mud" layer, and the thermal cycling performance and failure mechanism of the three new coatings were studied. The results showed that the agglomerated Y2O3 partially stabilized ZrO2 (YSZ) particles had porous spherical structures and good sprayability, and the content of the YSZ phase in the prepared "brick" layer was 54.2%. The "mud" layer had good phase stability and was amorphous SiO2 at and below 1100 °C. The fracture toughness of the pure YSZ coating was 2.295 ± 0.135 MPa‧m0.5, and which of the “mud” layer was reduced by 72.3%. The thermal cycling life of the conventional coating was only 67.3 times, which of A1, A2 and A3 coatings with 2, 3 and 6 "mud" layers were increased by 32.4%, 124.8% and 88.3%, respectively. In the thermal cycling process, the "weak" layer in the "brick-mud" layered coating led to the redistribution of internal stress and reduced the stress concentration in the top coating (TC)/TGO interface. Moreover, the initiation of microcracks in the "weak" layer, along with the "crack branching" effect and the "crack deflection" effect during the crack propagation process, could consume partial internal stress. Thus, the crack growth rates in the TC coating/TGO interface of the A1, A2 and A3coatings were lower than that of the conventional coating due to the above stress release mechanisms. In addition, the thermal cycling lives of the three new coatings with 2, 3 and 6 "mud" layers were improved to different degrees because of different stress effects.

An Ascorbic Acid-Imprinted Poly(o-phenylenediamine)/AuNPs@COFTFPB-NBPDA for Electrochemical Sensing Ascorbic Acid

An electrochemical sensor based on a molecularly imprinted polymer membrane (MIP) was developed. The electrochemical sensor was prepared by electropolymerization of o-phenylenediamine (O-PD) on the surface of glassy carbon electrode (GCE), modified by AuNPs@covalent organic framework (COF) microspheres with ascorbic acid (AA) as template molecule. First, ultrasmall polyvinylpyrrolidone (PVP)-coated AuNPs were prepared by a chemical reduction method. Then, 1,3,5-tri(p-formylphenyl)benzene (TFPB) and N-boc-1,4-phenylene diamine (NBPDA) underwent an ammonaldehyde condensation reaction on PVP-coated AuNPs to form AuNPs@COFTFPB-NBPDA microspheres. The porous spherical structure of AuNPs@ COFTFPB-NBPDA could accelerate the mass transfer, enlarge the specific surface area, and enhance the catalytic activity of PVP-coated AuNPs. The electrochemical sensors, based on AuNPs@ COFTFPB-NBPDA/GCE and nMIPs/AuNPs@COFTFPB-NBPDA/GCE, were applied for the detection of AA, with a detection limit of 1.69 and 2.57 μM, as well as linear ranges of 5.07 to 60 mM and 7.81 to 60 mM. The nMIPs/AuNPs@COFTFPB-NBPDA sensor had satisfactory stability, selectivity, and reproducibility for AA detection.

A Novel Formulation of Mesoporous Silica Nanoparticles Functionalized with Polyaniline Brush Polymer: Synthesis and Characterization

Mesoporous silica nanoparticles and polyaniline (PANI) are widely used in many potential applications. This work establishes a new formulation that functionalizes the surface of mesoporous silica MCM-41 nanoparticles with a brush polymer of polyaniline to synergistically combine their properties. The new formulation is designed to fit in many applications due to its high surface area and good electrical conductivity. Results showed the successful preparation of MCM-41 with a spherical porous structure. The polyaniline functionalization on MCM-41 was confirmed by FTIR.