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In this work, zeolitic imidazolate frameworks (ZIF-8) and carboxylated carbon nanotubes (CNTs) were compounded to prepare a kebab-like one-dimensional linear composite, ZIF-8@CNTs. The mixed-matrix membrane (MMM) for separating carbon dioxide is prepared by embedding it into the polymer matrix Pebax-1657. The results indicated the successful synthesis of the ZIF-8@CNT composite. The combination of ZIF-8 and carboxylated CNTs avoided the aggregation of ZIF-8 in the polymer, increased the free volume of the MMM, and enhanced the CO2 adsorption performance and CO2/N2 separation performance. In addition, the interaction between CNTs and ZIF-8 provided a fast transport channel for CO2 molecules and improved the mechanical properties of the MMM. The 5 wt % ZIF-8@CNT MMM showed the best separation performance with a CO2 permeability of 225.5 Barrer and a CO2/N2 selectivity of 48.9, which exceeded the Robeson upper limit in 2008. The combination of high permeability and selectivity made Pebax/ZIF-8@CNT MMMs promising for industrial CO2 separation applications.

Metal nanozymes hold promise for chemical and biological applications, and their implementation relies on high catalytic efficiency and stability. Using the metal-organic framework as an ideal carrier for well-dispersed ultra-small metal nanoparticles (NPs) is beneficial for improving the catalytic efficiency of nanozymes. In this study, a zirconium-based metal organic framework (UiO-66) with good chemical stability and high porosity was synthesized and used to construct Pt/UiO-66 nanocomposites. The percentage of Pt in UiO-66 can be tuned easily by adjusting the feeding amount of PtCl4 2-. Because of the confinement effect of mesopores, the Pt particles with an average diameter of 3.8 nm are formed and dispersed throughout the pores of the UiO-66 particle. The Pt/UiO-66 composites show efficient oxidase- and peroxidase-like activity. Both the oxidase- and peroxidase-like activities are dependent on the Pt percentage. Pt/UiO-66-6% exhibits enhanced peroxidase-like activity, ∼3.9 times higher than that of commercial Pt/C with 10 wt % Pt. We propose that the construction of Pt/UiO-66 increased the utilization efficiency and stability of Pt NPs and provided more active sites for catalytic reactions. Using the peroxidase-like activity of Pt/UiO-66, a colorimetric method that can be used for actual blood glucose detection was developed for the specific detection of glucose with a limit of detection of 0.033 mM.

The composition and structure of polyacrylonitrile (PAN) precursors play an important role during thermal stabilization, which influences the properties of the resulting carbon fibers. In this paper, PAN homopolymer and PAN-itaconic (IA) copolymers with different IA contents were synthesized by aqueous phase precipitation polymerization. The effects of IA content on the structure and thermal properties were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology of PAN polymers showed that the average size of the PAN particles increased with the increase of IA content in the feed. The content of the IA comonomer on the copolymers was quantitatively characterized by the relative absorbance intensity (A1735/A2243) in FTIR spectrum. With the increase of IA content in the feed, PAN-IA copolymers exhibited lower degree of crystallinity and crystal size than the control PAN homopolymer. The results from DSC curves indicated that PAN-IA1.0 copolymers had lower initial exothermic temperature (192.4 &deg, C) and velocity of evolving heat (6.33 J g&minus, 1 &deg, C&minus, 1) in comparison with PAN homopolymer (Ti = 238.1 &deg, C and &Delta, H/&Delta, T = 34.6 J g&minus, 1) in an air atmosphere. TGA results suggested that PAN-IA1.0 copolymers had higher thermal stability than PAN homopolymer, which can form a ladder structure easier during thermal processing. Therefore, PAN-IA1.0 copolymers would be a suitable candidate for preparing high performance PAN based carbon fibers.

Polyacrylonitrile (PAN) grafted amino-functionalized multi walled carbon nanotubes (amino-MWCNTs) were synthesized by in situ polymerization under aqueous solvent. The grafted MWCNT/PAN nascent composite fibers were prepared by the wet spinning method. Fourier transform infrared spectroscopy and Raman spectroscopy indicated that the amino-MWCNTs and PAN macromolecular chains had interfacial interactions and formed chemical bonds. The grafting content of the PAN polymer on the amino-MWCNTs was up to 73.2% by thermo gravimetric analysis. The incorporation of the grafted MWCNTs improved the degree of crystallization and crystal size of PAN nascent fibers, and changed the thermal properties during exothermic processing in an air atmosphere. Morphology analysis and testing of mechanical properties showed that the grafted MWCNT/PAN nascent composite fibers with a more uniform diameter distribution and larger diameter had higher tensile strength and tensile modulus than the control PAN nascent fibers.

Development of high-performance electrocatalyst for oxygen reduction reaction is imperative to address the issues of energy and environment. Zeolitic imidazolate frameworks (ZIFs)/carbon nanotubes (CNTs) composites have been regarded as a promising precursor to fabricate efficient catalysts. However, it is challenging to synthesize ZIF/CNT composites with unique structure and controllable compositions. Herein, a CNT-directing assembly strategy is developed to synthesize ZIF/CNT nanonecklaces with unique structure and tunable Zn/Co ratios. The oxidized CNTs are employed as a structure-directing agent to prepare one-dimensional nanonecklaces. The ratios of Co/Zn in the ZIF can be adjusted from 0 to 8:2 by simply changing the amount of metal precursors. After carbonization and acid leaching, Co nanoparticles are embedded in the graphitization carbon matrix. Zn species are removed completely and produce plenty of nanopores in the carbon framework. Such ZIF/CNT nanonecklaces derived carbon composites are further used as a catalyst for oxygen reduction reaction, which show high onset potential (0.92 V) and high limiting current density (5.31 mA cm−2 at 0.30 V). This work provides a new synthesis strategy for the fabrication metal/carbon composited catalysts.

Well-dispersed MgAl2O4 nanocrystalline was prepared by a convenient salt-assistant combustion process using low-toxic glycine as fuel, low-cost Mg(NO3)2·6H2O and Al(NO3)3·9H2O as raw materials. By changing the reaction condition such as glycine dosage, the amount of inert-salt, inert-salt types and calcinations temperature, the optimal conditions to synthesize MgAl2O4 nanocrystalline were explored. The obtained results showed that parameters inert-salt and fuel dosage in the process have an important effect on the structure properties of samples. The obtained products were characterized by XRD and TEM. TEM images revealed that the products were composed of well-dispersed cube-like nanocrystals with the size of 60–80 nm. The synthesis mechanism of MgAl2O4 nanocrystals was discussed. The crystal growth dynamics of MgAl2O4 nanocrystals was studied and the activation energy of MgAl2O4 nanocrystals was 39.1 kJ/mol.

A new pseudo-seeding and nano-scaffolding method was developed to synthesize thin ZIF-8 hybrid membranes (100–200 nm) with remarkable mechanical and structural stability and high H2 permeance (2.87 × 10−5 mol m−2 s−1 Pa−1) and selectivity over CO2 (14), N2 (18), CH4 (35), C3H6 (52.4) and C3H8 (950.1).

Er2Sn2O7 nanocrystals were successfully synthesized by salt-assistant combustion method (SACM) at a relatively low temperature (600 °C). The Er2Sn2O7 nanocrystals were characterized by XRD, FT-IR, TEM and HRTEM. The effect of thermal treatment temperature on the crystal size of nanocrystals was studied and the activation energy of Er2Sn2O7 nanocrystals formation during calcination was calculated to be 88.1 kJ/mol. TEM results showed that the Er2Sn2O7 nanoparticles obtained by SACM were well-dispersed and uniform in particle size distribution. The interplanar distance of d222 measured from the HRTEM images was 0.301 nm, coinciding with the theoretical value.

The yttrium zirconate (Y2Zr2O7) nanocrystals with cubic structure in the size range of 50 nm were prepared by stearic acid method (SAM) using zirconium nitrate and yttrium nitrate as raw materials, stearic acid as solvent and dispersant. The synthesis process was monitored by TG–DTA. The product was characterized by XRD, FT-IR, TEM, HRTEM, EDS and BET. The effect of thermal treatment temperature on crystal size and lattice distortion of the nanocrystals was studied. Y2Zr2O7 nanocrystals obtained by SAM were well dispersed with average size of 20–40 nm. The interplanar distances measured from the HRTEM image were 0.294 and 0.185 nm, respectively, coinciding with the theoretical values. Moreover, the photocatalytic properties of Y2Zr2O7 nanocrystals were measured and discussed.

Nanosized spinelCoAl2-xRexO4complex oxides were prepared by self-propagation combustion method. The products have been characterized by XRD, SEM, and EDS. The results indicated that Al3+can be partly replaced by Re3+when the doped amount is less than 10%, which forms single solid solution. The NIR reflectance and chromatic properties of samples have also been investigated. The substitution of Re3+for Al3+in CoAl2O4can increase the blueness of pigments. SEM results revealed that the obtainedCoAl2-xRexO4pigments consisted of highly dispersed spherical-like nanoparticles with uniform size distribution. EDS results indicated that the distribution of element was considerably uniform with no chemical segregation phenomenon.

The highly dispersed nanostructured NiTiO3pigments and NiTiO3/TiO2composite pigments can be synthesized at relative low temperature. The activation energy of crystal growth of NiTiO3during calcinations via salt-assistant combustion method is 9.35 kJ/mol. The UV-vis spectra results revealed that the absorbance decreased with the increasing of calcinations temperature due to small size effect of nanometer particles. The optical data of NiTiO3nanocrystals were analyzed at the near-absorption edge. SEM showed that the obtained NiTiO3nanocrystals and NiTiO3/TiO2nanocomposite were composed of highly dispersed spherical-like and spherical particles with uniform size distribution, respectively. The chromatic properties and diffuse reflectance of samples were investigated. The obtained NiTiO3/TiO2composite samples have higher NIR reflectance than NiTiO3pigments.

Well-dispersed nanocrystalline MnCr2O4was prepared by a salt-assisted combustion process using low-toxic glycine as fuel and Mn(NO3)2and Cr(NO3)3·9H2O as raw materials. The obtained products were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The fabrication process was monitored by thermogravimetric and differential thermal analysis (TG-DTA). The phase formation process was detected by XRD, and MnCr2O4single phase with high crystallinity was formed at 700°C. TEM and SEM images revealed that the products were composed of well-dispersed octahedral nanocrystals with an average size of 80 nm. Inert salt-LiCl played an important role in breaking the network structure of agglomerated nanocrystallites.