Nano

In this work, BiFeO₃ and BiCo${}_{0.08}$Fe${}_{0.92}$O₃ nanoparticles prepared by the solution method were further investigated the magnetic properties. At room temperature, BiFeO₃ reveals the antiferromagnetic order. However, Co doping achieves ferromagnetic enhancement. The room-temperature ferromagnetism and the causes are ulteriorly studied with the help of ABK plots. The stronger coercivity is due to the oxygen vacancies and stronger magnetic anisotropy caused by Co substitution. Under variable temperatures, the bifurcate curves of zero-field-cooled and field-cooled indicate the existence of spin-glass state for both samples. The weak ferromagnetism at low temperature and the spin-state transition of cobalt ions at 270K are also found.

Hierarchical hollow nano-/micro-architectures with complex multishelled structures are highly desirable for achievement of various functionalities. However, it is still a great challenge to integrate multinary compositions into a nonspherical hollow structure with complex multishells. Herein, we developed an effective strategy to construct hierarchical double-shelled NiCo-layered double hydroxides@MSiO₃ (NiCo-LDH@MSiO₃, M = Ni, Cu, Mn) hollow polyhedral nanocages with inner NiCo-LDH and outer MSiO₃ layers. Our design principle involved a one-pot synthesis of Co-based zeolitic imidazolate framework-67@SiO₂ (ZIF-67@SiO${}_2)$ core@shell polyhedrons and a subsequent two-step in situ chemical conversion reaction process. Benefiting from the structural merits including high specific surface area, abundant mass diffusion pathways, and the unique hierarchical hollow structures, the double-shelled NiCo-LDH@MSiO₃ hollow polyhedral cages exhibited significant adsorption capacity of Congo red. Especially, the maximum adsorption capacity of the double-shelled NiCo-LDH@NiSiO₃ hollow polyhedral cages could reach up to 510.6mg/g, implying a high efficiency for the removal of Congo red from aqueous solution and a potential application in water treatment.

A series of multicatalytic easily separable magnetic ceria (CeO₂-CoFe₂O₄) nanocomposites were prepared with different content of CoFe₂O₄ by the in-house developed double in situ hydrothermal method. The crystal structure, morphology and magnetic properties of the samples were characterized in detail with the help of X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). XRD patterns showed that a small amount of CoFe₂O₄ did not affect the crystal structure of ceria, and CeO₂-CoFe₂O₄ had typical characteristic peaks containing both ceria and CoFe₂O₄. SEM images show that CeO₂-CoFe₂O₄ samples were in the form of uniform cubical structures with particle sizes within 20–50nm. The VSM results demonstrated that the ferrimagnetic nature of CeO₂-CoFe₂O₄ sample was obvious and sample saturation magnetization increased with the CoFe₂O₄ content. The samples with different content of CoFe₂O₄ were further used in phosphate ions adsorption and artificial enzyme applications.

Cervical cancer is a common cause of cancer-related death in women worldwide, and quantitative detection of serum tumor markers has practical implications for diagnosing cervical cancer. In this study, a novel surface-enhanced Raman scattering (SERS)-based immunosensor for the hypersensitive simultaneous detection of survivin and osteopontin (OPN) in cervical cancer serum was proposed, which was composed of the AuNPs@SiO₂ microspheres (Au@SiO₂) array immunosubstrate and Au-Ag nanoshells (Au-AgNSs) immunoprobes. The experimental results demonstrated that the constructed SERS immunosensor exhibited satisfactory selectivity and reproducibility while possessing detection limits as low as 0.908pg/mL and 0.813pg/mL for survivin and OPN in human serum. Finally, its usefulness in real serum samples (from healthy subjects, cervical intraepithelial neoplasia 1 (CIN 1), CIN 2, CIN 3 and cervical cancer patients) was verified, and the detection data were in good agreement with the enzyme-linked immunosorbent assay results. This immunosensor has excellent performance, which is promising for the early screening of cancer.

Natural catalysts used in the synthesis of carbon nanotubes have significant cost advantages due to their huge reserves, but natural minerals often require complicated pretreatments to obtain satisfactory products. In this study, red sandstone was directly used as a catalyst for the synthesis of multi-carbon nanotubes by chemical vapor deposition without complicated pretreatment. The SEM, TEM, Raman and TG characterization of the products at different growth temperatures ($600^{\circ }$C, $700^{\circ }$C and $800^{\circ }$C) showed that $700^{\circ }$C is the optimal condition for the growth of multi-walled carbon nanotubes (MWCNTs) by red sandstone. High-quality multi-wall carbon nanotubes can be obtained with a relatively high yield, and the $I_G∕I_D$ of the product reaches 1.78, which exceeds that of many commercial multi-wall carbon nanotubes. Compared with other natural materials as catalysts for the synthesis of MWCNTs, red sandstone has a huge cost advantage because it can catalyze the synthesis of high-quality MWCNTs at $700^{\circ }$C without complicated pretreatment.

Single and coaxial electrospraying techniques are superior nanofabrication methods for nanomaterial production. These nanomaterials have the unique capability to manipulate various surfaces and bring diverse additional functionalities. The objectives of the present study are to produce poly(lactic acid) (PLA)/chitosan nanoparticles and investigate the synergy of nanosize effect with different morphology structures in terms of achieved functionality. The impact of ambient humidity on coating morphology was examined via a scanning electron microscope, field emission scanning electron microscope and dynamic light scattering for size measurements and dimensional characterization of nanoparticles. The obtained results indicate that electrosprayed PLA polymer shows a tendency to have a more distinct pore structure than electrosprayed chitosan polymer. Humidity has an increasing effect on particle size. Another finding is the relationship between hygroscopic characteristics of polymer with nanoparticle size, polydispersity, surface morphology and pore structure. Overall, these methods introduced high antibacterial activity obtainment on electrosprayed surfaces. Up to 99.99% antibacterial activity was accomplished against Escherichia coli ($E.coli$) and Staphylococcus aureus (S. aureus) bacteria in regard to this study. The created surface layers also have the extensive potential of practicability for diversified kinds of surfaces and numerous combinations of polymers for multifunctional applications.

Because of the decrease in the band gap and the carrier recombination rate, the visible light photocatalysis performance of the mixed-phase TiO₂ with oxygen vacancies is better than that of the pure-phase TiO₂. In this study, two different acids were separately applied in the hydrothermal synthesis of TiO₂ nanoparticles without any post-heat treatment. The reaction was carried out at a relatively low temperature not exceeding 140^∘C. Both kinds of crystallized TiO₂ powders show much more band gap reduction than that of commercial Degussa P25 TiO₂ nanoparticles, which can be attributed to the oxygen vacancies. Under the visible light illumination-assisted photocatalytic degradation of methyl orange in water, the two mixed-phase TiO₂ powders exhibited a steady photocatalytic activity upon increasing to five cycles. The highest photocatalytic efficiency of the two powders is 2.7 times than that of the P25 powder, which is regarded as an excellent photocatalyst for water purification.

Volatile organic compounds (VOCs) are the one kind of pollution, which lead to the severe atmospheric contamination problem. Metal organic frameworks (MOFs) and graphene are promising candidates to collect VOCs. In this study, composites which consist of graphene sheets and Cu-BTC (benzene-1,3,5 tricarboxylic acid) are prepared by the hydrothermal method to adsorb VOCs and CO. Moreover, the morphology of the resulting graphene material in the composites can be controlled by adjusting the pH value, reaction time and surfactant during the hydrothermal process, which further determines the adsorption ability for different gas molecules. According to the pore distribution features of various composites, the morphology of graphene exerts a fatal influence on the observed adsorption performances. Furthermore, the polarity of the as-prepared composites is another important determinant to selective adsorption for various VOCs. The stability of these composites under high temperature is also tested, and the results demonstrate that the adsorbents can be used in a wide temperature range. Moreover, the large BET areas and high stability of the composites in the water endow them a potential application in the sewage clarification field. After the corresponding optimization, the adsorption amounts of methanol and ethanol reach 13.6mmolg${}^{-1}$ and 9.68mmolg${}^{-1}$, respectively.

CaMoO₄ nanoparticles/graphene oxide (CaMoO₄/GO) composites are prepared by a facile hydrothermal method. CaMoO₄ nanoparticles are adsorbed on the GO sheets by in situ reduction. Along with the synergistic effect between the CaMoO₄ and GO sheets, the CaMoO₄/GO nanocomposites exhibited high performances as electrodes for supercapacitors. The specific capacity ($Q_s)$ of the CaMoO₄/GO electrodes could be up to 571.82F$\cdot$g${}^{-1}$ at 0.5A$\cdot$g${}^{-1}$. Furthermore, asymmetric supercapacitors (ASCs) are mainly composed of CaMoO₄/GO composite and activated carbon (AC), respectively. The fabricated CaMoO₄/GO//AC devices display an energy density of 25.18W$\cdot$h$\cdot$kg${}^{-1}$ at 1710.3W$\cdot$kg${}^{-1}$. A blue LED is powered using two series-connected two ASC devices. These results indicate the considerable potential of CaMoO₄/GO for use in high-performance energy storage devices.