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A series of MXene/MnCo 2 O 4.5 nanocomposites was successfully prepared by hydrothermal, ice crystal template and physical blend methods, respectively. Various characterizations indicated that hydrothermal method could successfully loaded MnCo 2 O 4.5 nanoparticles on the surface of MXene nanosheets to obtain MMC-W nanocomposites with 3D flower-like structure, which could give MMC-W large specific surface area. The HTD temperature and decomposition heat of AP with adding 2.0 wt% MMC-W could significantly decrease to 304.7 °C and increase to 1310.9 J g-1, respectively. The lowest decomposition temperature (286.1 °C) and the highest heat release (1427.6 J g-1) of AP could be obtained by adding 8.0 wt% and 4.0 wt% of MMC-W, respectively. Moreover, MMC-W (2.0 wt%) could also significantly reduce the E a of pure AP by 118.3 kJ mol-1 and increase the k value for AP by 11.2 times. The excellent catalytic performance of MMC-W was owing to the synergistic effect of nano-sized MnCo 2 O 4.5 and MXene nanosheets. Owing to its high catalytic activity, MMC-W would be used as an excellent catalyst for ameliorating AP decomposition and supply an idea for the preparation of novel metal oxide nanoparticles. [Display omitted] • Three methods were used to prepare MXene/MnCo 2 O 4.5 nanocomposites as catalysts. • MMC-W with flower-like structure exhibited high specific surface area. • MMC-W exhibited an excellent catalytic performance for AP decomposition. • MMC-W reduced the activation energy of AP decomposition by 118.3 kJ mol-1. • The synergistic effect of nano-sized MnCo 2 O 4.5 and MXene promoted AP decomposition. [ABSTRACT FROM AUTHOR]

Considering the significant role of metal nanoparticles in the detection and removal of pollutants from the environment, metal oxides stand as inexpensive materials at the scale of nanometers that are capable of participating in photocatalytic and decontamination procedures. Meanwhile, nickel nanoparticles have been applied as a new approach for removing the existing pollution from the environment. In this paper, we have synthesized copper doping nickel oxide nanoparticles (Cu-doped NiO-NPs) by a sol-gel method that involved the application of okra plant extract and had investigated their photocatalytic properties and cytotoxicity effects. The obtained Cu-doped NiO-NPs have been characterized through FT-IR, UV–Vis, XRD, FESEM/EDAX/PSA, and VSM analyses in different concentrations (1, 3, and 5%) of copper at an optimum temperature of 400 °C. According to the XRD results, the size of nanoparticles under optimal conditions (at the temperature of 400 °C and % 3 Cu-doped) has been observed to be 10.66 nm while containing a face-centered cubic (fcc) structure. Furthermore, the obtained FESEM outcomes have been indicative of the good dispersion of these nanoparticles. Also, photocatalytic activity of Cu-doped NiO-NPs through the degradation of methylene blue (MB) pigment studied under UV-A light and had detected 78% of degradation throughout 105 min. To complete the characterization process, the cytotoxicity of nanoparticles in inhibiting the cancer CT26 cells has been determined using of MTT assay. [Display omitted] [ABSTRACT FROM AUTHOR]

The large-scale synthesis and the stabilization of noble metal nanocatalysts with ultrasmall sizes are crucial to their practical application. Herein, Pd, Au, and Pt nanoparticles (NPs) are in situ embedded on boron nitride nanosheets (BNNSs) via the reduction of precursor salts induced by 60Co γ-irradiation, which is a mature technique widely used in industry. The reduction mechanism was elucidated by pulse radiolysis experiments. In comparison with other BN substrates like hexagonal BN (h -BN), BNNSs had not only large surface area of 263 m2 g−1, but also abundant hydroxyl groups produced during the sonicated exfoliation, resulting in ultrasmall sizes, large loading amounts, and uniform distribution of the anchored NPs. The particle sizes of the loaded Pd, Au, and Pt NPs were measured to be 2.9, 3.1, and 3.0 nm, respectively. As a consequence, in the model reaction of 2-nitroaniline reduction, the Pd-, Au- and Pt-BNNSs composite nanocatalysts showed much higher catalytic activities than those composites loading the corresponding NPs on other BN substrates. Particularly, most of the 2-nitroaniline could be reduced within merely 40 s when using Pd-BNNSs as catalysts, performing a rate constant of 1.1 × 10−1 s−1. The number of hydroxyl groups on BNNSs support as well as the catalytic performance of the corresponding NPs-loaded BNNSs composites could be improved by extending the sonicated exfoliation time, because more NPs were loaded and the hydroxyl groups were also proved to play an important role in enhancing the catalytic activity. Moreover, Pd-BNNSs catalysts still displayed prominent activity even after five cycles owing to the high stability of BNNSs and their strong affinity for PdNPs. This work not only demonstrates BNNSs as ideal supports to load noble metal NPs for catalysis, but also reveals the feasibility to synthesize and in situ embed ultrasmall noble metal NPs on BNNSs via γ-irradiation. γ-Radiation-induced reduction achieved facile loading of noble-metal nanoparticles on BNNSs as ideal supports for extraordinary catalytic activity and excellent reusability. [Display omitted] • BNNSs with hydroxyl groups, prepared from sonicated exfoliation, were suitable to load noble metal nanoparticles (NPs). • Noble metal NPs of Pd (Au or Pt) were in situ embedded on BNNSs by facile γ-radiation-induced reduction. • The reduction mechanism was elucidated by pulse radiolysis experiments. • NPs loaded on BNNSs possessed the smaller sizes and higher loading amounts, compared with those on other BN substrates. • NPs-loaded BNNSs showed excellent catalytic activity and reusability for 2-nitroaniline reduction. [ABSTRACT FROM AUTHOR]

The divalent metal aluminate spinels were synthesized by autoignition of gel systems containing metal (Al, Mg, Co and Zn) nitrates and glycine as a fuel. A mechanism for nanoparticle formation was proposed from dried gel autoignition to calcination. The simultaneous differential thermal and thermo-gravimetric analyses were applied to understand the nature of process. Independently, the polymeric matrixes exhibited typical self-propagating combustion behaviors at low temperatures, 220–275 °C. The heat treatment was carried out on as-formed foamy materials to achieve the well crystallized spinels in nano-scale. The calcined products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area measurements and transmission electron microscopy. Based on the resultant powders, the purity, crystallite size and specific surface area of spinels are directly related to cation type. The crystallized particles, having diameters smaller than 20 nm, could be successfully synthesized through optimized process variables. [ABSTRACT FROM AUTHOR]

GdVO 4 nanoparticles were prepared by a sol–gel method employing tartaric acid as a chelating agent. Effects of calcination temperature and mole ratio of total metal ions to tartaric acid on the products were investigated. The products, characterized by XRD, FESEM and TEM, were tetragonal GdVO 4 nanoparticles with diameters of about 20–30 nm. TG and DSC data showed weight loss and phase formation due to evaporation and decomposition processes. FTIR presented the stretching band of VO 4 3 − tetrahedrons and Raman analysis revealed the vibrational modes of the GdVO 4 . [ABSTRACT FROM AUTHOR]

Tungsten oxide (WO 3 ) nanoparticles have been successfully synthesized by sol–gel method for detection of NO 2 gas in the low concentration range (5–100 ppm). The sensor based on WO 3 was fabricated on glass substrate using simple and cost effective drop casting method. The structure and morphology of WO 3 nanoparticles were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. X-ray photoelectron spectroscopy (XPS) confirms formation of WO 3 . The chemiresistive gas sensing performance of WO 3 films were studied towards various reducing (NH 3 , H 2 S, CH 3 OH & C 2 H 5 OH) and oxidizing (NO 2 & Cl 2 ) gases in the 100–300 °C temperature range. The experimental results demonstrate that, WO 3 films were highly sensitive and selective towards NO 2 gas than other test gases. The relationship between sensor response and various concentrations of NO 2 gas was systematically studied and explored. WO 3 thin films exhibit maximum response of 34% (towards 100 ppm NO 2 ) with very fast response time of 24 s and are able to detect low concentration of 5 ppm NO 2 gas with response of 16%. The proposed sensing mechanism of WO 3 thin films in presence of air and NO 2 gas was discussed. Furthermore, the interaction of NO 2 gas with WO 3 film was also investigated using impedance spectroscopy. [ABSTRACT FROM AUTHOR]

GdVO 4 nanoparticles were prepared by a sol–gel method employing tartaric acid as a chelating agent. Effects of calcination temperature and mole ratio of total metal ions to tartaric acid on the products were investigated. The products, characterized by XRD, FESEM and TEM, were tetragonal GdVO 4 nanoparticles with diameters of about 20–30 nm. TG and DSC data showed weight loss and phase formation due to evaporation and decomposition processes. FTIR presented the stretching band of VO 4 3 − tetrahedrons and Raman analysis revealed the vibrational modes of the GdVO 4 . [ABSTRACT FROM AUTHOR]

Abstract: Yttrium oxide (yttria) nanoparticles were successfully synthesized via a simple modified precipitation route in the presence of different surfactants. The effects of surfactant type on structure, morphology and luminescence properties were studied using X-ray diffractometer (XRD), scanning and transmission electron microscope (SEM and TEM) and photoluminescence (PL) techniques. Different types of surfactants including nonionic, anionic and cationic were used at 50% of their critical micelle concentration (CMC) point. Also, the surfactant concentration and synthesis temperature were investigated for M2P surfactant. Microstructure and PL analysis showed that the maximum PL intensity was obtained for the cationic surfactant due to the more uniform morphology and size as well as more homogeneous distribution of nanoparticles. Also, the results demonstrated that surfactant concentration has a vital effect on morphology and fluorescent properties of the nanoparticles. [Copyright &y& Elsevier]

Abstract: The effect of high-energy ball milling on the textural evolution of alumina nanopowders (compaction response, sinter-ability, grain growth and the degree of agglomeration) during post sintering process is studied. The applied pressure required for the breakage of the agglomerates (P y) during milling was estimated and the key elements of compressibility (i.e. critical pressure (P cr) and compressibility (b)) were calculated. Based on the results, the fracture point of the agglomerates decreased from 150 to 75MPa with prolonged milling time from 3 to 60min. Furthermore, the powders were formed by different shaping methods such as cold isostatic press (CIP) and uniaxial press (UP) to better illustrate the influence of green compact uniformity and powder deagglomeration on the densification behavior of nanopowders. [Copyright &y& Elsevier]

Abstract: The use of plant extract in the synthesis of nanostructured materials can be a cost effective and eco-friendly approach. In this paper we report the biosynthesis of zinc oxide nanoparticles using Citrus aurantifolia extracts. Spherical zinc oxide nanoparticles were produced using different concentration of zinc acetate which was used as the zinc source. FESEM imaging showed the formation of nanoparticles in the size range of 50–200nm. XRD analysis revealed wurtzite hexagonal ZnO with preferential orientation at (100) reflection plane. The room temperature PL spectroscopy showed little variation for samples deposited with different zinc acetate concentration. Peak due to V o +, V o , hole trapped at V o ⁎⁎, O i and hydroxyl groups were observed with slight variation in peak position. The synthesis of zinc oxide nanoparticles using the citrus extracts were found to be comparable to those obtained from conventional reduction methods using hexamethylenetetramine or cetyltrimethylammonium bromide and can be an excellent alternative for the synthesis of ZnO nanoparticles using biomaterials. [Copyright &y& Elsevier]