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Benefiting from the enhanced POD-like activity of Au/UiO-66, multi-target detection of glucose, dopamine and sulfide ion was realized based on a distinct mechanism.

This paper presents a study on the effect of luffa fibres by different chemical treatments of luffa fibres on cracking resistance and drying shrinkage of cement mortar. This research is aimed at using natural vegetable fibres to improve the performance of cementitious materials for sustainable construction. XRD was carried out to characterize the crystallinity of treated luffa fibres. By changing the chemical treatment parameters, the relationship between different treatment conditions and crystallinity index was investigated. SEM was used to characterize the microstructure of luffa fibres. The early cracking and drying shrinkage of cement mortar with the addition of treated luffa fibres were experimentally studied. The results revealed that treated luffa fibres had a stronger effect on the early cracking than untreated luffa fibres, while the effect on the drying shrinkage of cement mortar was comparable between treated and untreated luffa fibres.

The aim is to explore a novel and controllable method to fabricate Re-doped Y2Zr2O7 nano solid solutions. The XRD results indicated that the Y ion can be replaced by other trivalent rare earth ion such as La, Nd, Sm, Dy and Er and the crystal form of Y2Zr2O7 remained unchanged. The crystal growth dynamics during calcinations via polymer precursor method were studied and the activation energy of crystal growth was calculated. TEM results indicated the obtained particles were spherical-like in the size of 30–50 nm with the uniform size distribution. The UV–vis absorption spectra of YNdZr2O7 precursor calcined at different temperatures were investigated. It can be seen that the crystal size has an effect on the absorbance. The band gap of YNdZr2O7 precursor calcined at different temperatures was in the range of 3.24~3.56 eV.

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.

Nanocrystalline Nd{sub 2}(Zr{sub 1-x}Sn{sub x}){sub 2}O{sub 7} series solid solutions were prepared by a convenient salt-assisted combustion process using glycine as fuel. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The results showed the Zr ion can be partially replaced by Sn ion. The partial substituted products were still single-phase solid solutions and the crystal form remained unchanged. TEM images reveal that the products are composed of well-dispersed square-shaped nanocrystals. The method provides a convenient and low-cost route for the synthesis of nanostructures of oxide materials.

Ultrafine fluorite type Dy{sub 2}Zr{sub 2}O{sub 7} nanocrystals with cubic structure were fabricated at relatively low temperature by stearic acid method (SAM) using zirconium(IV) butoxide and dysprosium nitrate as raw materials, stearic acid as solvent and dispersant. The fabrication process was monitored by thermogravimetric analysis and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FT-IR). The obtained products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrometer (EDS) and UV-vis absorption spectroscopy. A single phase of Dy{sub 2}Zr{sub 2}O{sub 7} with high crystallinity was formed at 800 deg. C. The interplanar distances measured from the HRTEM image were 0.284 and 0.256 nm, respectively, coinciding with the theoretical values.

Fine-particle rare-earth metal zirconates Ln 2 Zr 2 O 7 (Ln = La, Nd, Sm, Dy, Er) with cubic structure were prepared by stearic acid method. Zirconium nitrate and rare-earth nitrate were as raw materials, and stearic acid was used as solvent and dispersant. The as-prepared Ln 2 Zr 2 O 7 nanocrystals were characterized by XRD, FT-IR, TEM and HRTEM. The results showed that the preparation temperature was lowered (from 1500 °C to 800 °C) and the reaction time was shortened (from at least 10 h to 5 h) by stearic acid method, compared with transitional solid-state method. The photocatalytic activity of Ln 2 Zr 2 O 7 nanocrystals was evaluated by the photocatalytic degradation of methyl orange. With the increase of the atomic number, the photocatalytic activity trend of obtained Ln 2 Zr 2 O 7 (Ln = La, Nd, Sm, Dy, Er) nanocrystals was in agreement with the change trend of magnetic moment of the rare-earth metal ion. The photoactivity of Ln 2 Zr 2 O 7 was strongly dependent on Ln, decreasing in the sequence of Dy > Nd > Er > Sm > La.

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.

Pyrochlore La2Zr2O7 nanocrystals with cubic structure were prepared by stearic acid combustion method using zirconium nitrate and lanthanum nitrate as raw materials, stearic acid as solvent and dispersant. The La2Zr2O7 was characterized by XRD, Raman, FT-IR, BET, TEM, HRTEM and Emission/excitation spectra. The effect of thermal treatment temperature on crystal size of the nanocrystals was studied and a single phase of La2Zr2O7 was completely formed at 900 °C. The interplanar distances of d222 and d400 measured from the TEM images were 0.322 nm and 0.263 nm, respectively, coinciding with the theoretical values. Moreover, the strong fluorescent property of the La2Zr2O7 was measured, with the maximum emission peak at ca. 389 nm upon excitation at ca. 324 nm.