Thermal sprayed ceramic coatings have extensively been used in components to protect them against friction and wear. However, the poor lubricating ability severely limits their application. Herein, yttria-stabilized zirconia (YSZ)/MoS2 composite coatings were successfully fabricated on steel substrate with the combination of thermal spraying technology and hydrothermal reaction. Results show that the synthetic MoS2 powders are composed of numbers of ultra-thin sheets (about 7 ~ 8?nm), and the sheet has obvious lamellar structure. After vacuum impregnation and hydrothermal reaction, numbers of MoS2 powders, look like flowers, generate inside the plasma sprayed YSZ coating. Moreover, the growing point of the MoS2 flower is the intrinsic micro-pores of YSZ coating. The friction and wear tests under high vacuum environment indicate that the composite coating has an extremely long lifetime (>?100,000 cycles) and possesses a low friction coefficient less than 0.1, which is lower by about 0.15 times than that of YSZ coating. Meanwhile, the composite shows an extremely low wear rate (2.30?×?10?7 mm3 N?1 m?1) and causes slight wear damage to the counterpart. The excellent lubricant and wear-resistant ability are attributed to the formation of MoS2 transfer films and the ultra-smooth of the worn surfaces of hybrid coatings. 相似文献
Opening catalytically active sites in metal organic frameworks is an issue of fundamental importance for the development of effective and efficient catalysts. In this work, we first reported two metal metalloporphyrin–organic frameworks (MMPFs) with unoccupied pyridine groups as base catalysts. The reaction of Mn(II) and Co(II) with 5,10,15,20-tetrapyridylporphyrin produces two different metal metalloporphyrin–organic frameworks, {[(MnTPyP)]·H2O}n (MMPF-Mn) and [(CoTPyP)]n (MMPF-Co) (TPyP = 5,10,15,20-tetrapyridylporphyrin) under hydrothermal conditions. These two MMPFs have been fully characterized by single-crystal X-ray diffraction, powder XRD, elemental analysis and thermogravimetry (TG). MMPF-Mn displays a 3D network with a nbo topology, large and open hexagonal channels, MMPF-Co reveals a 1D single zigzag chain architecture. Interestingly, both MMPFs have a high thermal stability and opening basic pyridine group, which have been tested for the base catalyzed Knoevenagel condensation reaction. The catalytic study has demonstrated that MMPF-Mn catalysts having exposed pyridine group within 1D channel displayed an excellent performance for Knoevenagel condensation reaction. When MMPF-Mn was recycled four times, its catalytic activity remained with an inconspicuous decrease. We attribute MMPF-Mn showing a better performance than MMPF-Co to its active sites being aligned in extra-large cavity with an interior diameter of 20 Å. 相似文献
Advanced protein-based nanomaterials and nanosystems (PNNS) have attracted considerable scientific interest in recent decades due to their potential in bio-applications. Nowadays, the constructed PNNS exhibit different properties for various special applications based on the characteristics of different proteins. Herein, in this review article, a systematic summary and discussion focusing on designing multi-functional PNNS are presented. The latest developments in unique synthesis strategies and detailed classification of PNNS are reviewed. The functions of proteins in PNNS for biomedical applications, such as targeting proteins, carriers, enzymes, and fluorescent indicators, are summarized. Finally, the challenges and forward-looking perspectives of PNNS research are provided. 相似文献
Ethanol steam reforming (ESR) is one of the potential processes to convert ethanol into valuable products. Hydrogen produced from ESR is considered as green energy for the future and can be an excellent alternative to fossil fuels with the aim of mitigating the greenhouse gas effect. The ESR process has been well studied, using transition metals as catalysts coupled with both acidic and basic oxides as supports. Among various reported transition metals, Ni is an inexpensive material with activity comparable to that of noble metals, showing promising ethanol conversion and hydrogen yields. Additionally, different promoters and supports were utilized to enhance the hydrogen yield and the catalyst stability. This review summarizes and discusses the influences of the supports and promoters of Ni-based catalysts on the ESR process. 相似文献
Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as attractive alternatives for next-generation battery systems, which have promising application potential due to their earth abundance of potassium and sodium, high capacity and suitable working potential, however, the design and application of bi-functional high-performance anode still remain a great challenge up to date. Bismuth sulfide is suitable as anode owing to its unique laminar structure with relatively large interlayer distance to accommodate larger radius ions, high theoretical capacity and high volumetric capacity etc. In this study, dandelion-like Bi2S3/rGO hierarchical microspheres as anode material for PIBs displayed reversible capacity, and 206.91 mAh·g−1 could be remained after 1,200 cycles at a current density of 100 mA·g−1. When applied as anode materials for SIBs, 300 mAh·g−1 could be retained after 300 cycles at 2 A·g−1 and its initial Coulombic efficiency is as high as 97.43%. Even at high current density of 10 A·g−1, 120.3 mAh·g−1 could be preserved after 3,400 cycles. The Na3V2(PO4)3@rGO//Bi2S3/rGO sodium ion full cells were successfully assembled which displays stable performance after 60 cycles at 100 mA·g−1. The above results demonstrate that Bi2S3/rGO has application potential as high performance bi-functional anode for PIBs and SIBs.
An intervening barrier for photocatalytic water decomposition and pollutant degradation is the frustratingly quick recombination of e− - h+ pairs. Delicate design of heterojunction photocatalysts by coupling the semiconductors at nanoscale with well-matched geometrical and electronic alignments is an effective strategy to ameliorate the charge separation. Here a facile and environment-friendly l-cysteine-assisted hydrothermal process under weakly alkaline conditions is demonstrated for the first time to fabricate ZnIn2S4/In(OH)3 hollow microspheres with intimate contact, which are verified by XRD, SEM, (HR)TEM, XPS, N2 adsorption-desorption, UV–Vis DRS and photoluminescence spectra. ZnIn2S4/In(OH)3 heterostructure (L-cys/Zn2+ = 4, molar ratio) with a band-gap of 2.50 eV, demonstrates the best photocatalytic performance for water reduction and MB degradation under visible light, outperforming its counterparts (In(OH)3 and ZnIn2S4). The excellent activity of ZnIn2S4/In(OH)3 heterostructure arises from the intercrossed band-edge positions as well as the unique hollow structure with large surface area and wide pore-size distribution, which are beneficial for the efficient charge migration from bulk to surface as well as at the interface between ZnIn2S4 and In(OH)3. This work provides an efficient and eco-friendly strategy for one-pot synthesis of heterostructured composites with intimate contact for photocatalytic application. 相似文献
In this study, we investigated the effects of substituting Li+ for Co2+ at the B sites of the spinel lattice on the structural, magnetic and magnetostrictive properties of cobalt ferrites. The Li+ substituted cobalt ferrites, Co1-xLixFe2O4, with x varying from 0 to 0.7 in 0.1 increments, were synthesized with a sol-gel auto-combustion method using the cathode materials of spent Li-ion batteries. X-ray diffraction analysis revealed that all the Co1-xLixFe2O4 nanopowders had a single-phase spinel structure and the lattice parameters decreased with increasing Li+ content, which can be proved by slight shifts towards higher diffraction angle values of the (311) peak. Field emission scanning electron microscopy was used to observe the fractured inner surface of the sintered cylindrical rods and the increased porosity resulted in a decreased magnetostriction. The oxidation states of Co and Fe in the cobalt ferrite samples were examined by X-ray photoelectron spectroscopy. High resolution transmission electron microscopy micrographs showed that most particles were roughly spherical and with sizes of 25–35?nm. Li+ substitution had a strong effect on the saturation magnetization and coercivity, which were characterized with a vibrating sample magnetometer. The Curie temperature was reduced due to the decrease in magnetic cations and the weakening of the exchange interactions. The magnetostrictive properties were influenced by the incorporation of Li+ at the B sites of the spinel structure and correlated with the changes in porosity, magnetocrystalline anisotropy and the cation distribution. 相似文献
AbstractGraphene oxide (GO) was functionalized by polyether amine (PEA) via two methods which were one-pot modification in acetone (GON) and two steps with the intermediate product of GOCO-Cl generated (GONS). There were more PEA successfully grafted onto GO for GONS than GON. The onset polymerization temperatures of the benzoxazine (Bz) composites decreased by the inclusion of 1?wt% of GO, GON or GONS. Thermal stability of the polybenzoxazine (PBz) composites was significantly improved indicated from the increase of weight loss temperature. T10, T20 and T50 values of the composites with GONS were higher than that of the others. Toughness of PBzs may be enhanced by the incorporation of nanofillers, and GONS had stronger interfacial interaction with PBz matrix than GON. 相似文献