•Ag/TiN-Ag composite multilayers are deposited on medical Ti-6Al-4V.•The structure, mechanical and biological properties depend on different Λ.•Smaller Λ gives a positive contribution to mechanical properties.•The highest hardness and critical load reach 35.983 GPa and 38 mN at 10 nm-Λ.•The composite multilayers with Λ = 10 nm show better living cell growth.Ag/TiN-Ag composite multilayers were deposited on Si and Ti-6Al-4V substrates using a multi-target magnetron co-sputtering system. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the Ag/TiN-Ag composite multilayers exhibited a weaker TiN textures with the smaller modulation period (Λ), which proved the smaller Λ can block the growth of columnar grain and particle, inducing a smoother surface and smaller roughness parameters (Ra: 0.82 nm; Rq: 1.2 nm). Ag existence in the surrounding TiN in top TiN-Ag composite layer and Ag layer insertion into TiN layer prohibited the emergence and propagation of cracks and prevented the growth and dislocation slip of defects, thus limited TiN grain size in a nanoscale size (5–10 nm), which enhanced the hardness and adhesion strength of the multilayers with smaller Λ. The hardness, elastic modulus and critical load reached 35.983 GPa, 426.937 GPa and 38 mN, respectively, when Λ was 10 nm. The population of living cells growing on the composite multilayers with Λ = 10 nm was far higher than those of other tested groups. This work proved the Ag/TiN-Ag composite multilayer with smaller Λ was beneficial for improvement of hardness, adhesion strength and living cells growth.

•The HfN/HfB2 multilayers were produced by magnetron sputtering.•The different grain sizes were obtained by controlling the modulation periods.•Higher H/E ratio, the highest critical fracture load appeared at 40 nm-Λ.•Lower residual stress and lower friction coefficient were also observed at 40 nm-Λ.•40 nm-Λ is an optimal value to improve the performances of the multilayers.A series of the HfN/HfB2 nanomultilayers with different modulation periods (bilayer thickness, Λ) were synthesized via a magnetron sputtering system. The X-ray diffraction (XRD) and cross-sectional scanning electron microscope (SEM) measurements indicated that all the HfN/HfB2 multilayers showed a lower crystallization and a columnar microstructure at the lower Λ values ranging from 20 to 50 nm. When the Λ varied from 90 to 150 nm, the multilayers presented the strong polycrystalline and fine-grained microstructure. Owing to the existence of excess B elements measured by X-ray photoelectron spectroscopy (XPS) in the HfB2 layer that prevented grain-boundary sliding, the highest hardness (42.58 GPa) and elastic modulus (519.27 GPa) values were reached at Λ of 150 nm. However, the higher H/E ratio (0.098) and lower friction coefficient (0.059) appeared at a lower Λ value of 40 nm. The lower residual stress (− 1.02 GPa) and the highest critical fracture load (Lmax = 68.8 mN) were also obtained at Λ = 40 nm. The smaller grain size at the lower Λ should be one of the main contributions to the improved mechanical properties. So, the modulation period might be a key parameter to control the microstructure and the mechanical properties of the HfN/HfB2 multilayers.

•Interfacial structure of TaN/ReB2 multilayers was calculated using DFT.•Different interfacial configurations of TaN(100)/ReB2(001) were chosen.•Re-N2 interface was the most stable configuration by calculation.•The calculated Mulliken population and electrons number predicted the mechanical properties.Interface structure of TaN/ReB2 multilayers was investigated using first-principles based on density functional theory (DFT). The hexagonal TaN and hexagonal ReB2 were chosen in this paper, and nine different interfaces of TaN(100)/ReB2(001) were chosen to calculate the interface energy, taking into account both N- and Ta-terminations. The interfacial electronic properties including charge density distribution, states of density (DOS) and Mulliken population were simulated to determine the nature of interface bonding. The results showed that B-N interface had the strongest bonding combined covalent bonding. The Re-N2 interface was the most stable interface. Meanwhile, Mulliken population and number of electrons of interface were calculated to predict the mechanical properties of monolithic TaN and ReB2 coatings and TaN/ReB2 multilayers.

•Sn/SnO2/porous carbon nanocomposites are rationally designed via a facile strategy.•The porous carbon mitigates the volume change and poor conductivity of Sn/SnO2.•The nanocomposites exhibit the enhanced sodium storage performance.Sodium-ion batteries (SIBs) have successfully attracted considerable attention for application in energy storage, and have been proposed as an alternative to lithium ion batteries (LIBs) due to the abundance of sodium resources and low price. Sn has been deemed as a promising anode material in SIBs which holds high theoretical specific capacity of 845 mAh g−1. In this work we design nanocomposite materials consisting of porous carbon (PC) with SnO2 and Sn (Sn/SnO2/PC) via a facile reflux method. Served as an anode material for SIBs, the Sn/SnO2/PC nanocomposite delivers the primary discharge and charge capacities of 1148.1 and 303.0 mAh g−1, respectively. Meanwhile, it can preserve the discharge capacity approximately of 265.4 mAh g−1 after 50 cycles, which is much higher than those of SnO2/PC (138.5 mAh g−1) and PC (92.2 mAh g−1). Furthermore, the Sn/SnO2/PC nanocomposite possesses better cycling stability with 77.8% capacity retention compared to that of SnO2/PC (61.88%) over 50 cycles. Obviously, the Sn/SnO2/PC composite with excellent electrochemical performance shows the great possibility of application in SIBs.Download high-res image (108KB)Download full-size image

The poriferous reduced graphene oxide (rGO) with abundant oxygen-containing functional groups synthesized by a one-step hydrothermal method was successfully employed as a high performance cathode in lithium-ion batteries. The electrochemical results show that the rGO exhibits a remarkable lithium storage capacity (up to 270 mA h g−1 after 100 cycles). Further analysis shows that the rGO can exhibit a significantly high rate capacity, good reversibility, and excellent cycling stability, which clearly reveals the potential use of the rGO as the cathode material to boost both energy and power densities of LIBs. Furthermore, by controlling the oxygenic functional groups of the rGO, it was demonstrated that the capacity of rGO increased with the increase of the number of oxygenic functional groups, which illustrates that the excellent electrochemical performance of rGO could be attributed to its specific poriferous structure and the oxygen-containing functional groups.

•The graphene with oxygen-containing functional groups were synthesized.•The graphene cathode showed high specific capacity and excellent cyclability.•Oxygen-containing functional group is the significant key as reaction center.•The proposed route exhibited some promising possibilities for mass production.Exploring high performance and environment-friendly electrode materials is highly desirable for the sustainable Li-ion batteries (LIBs) system. In this study, a facile approach of the modified Hummers’ method combining with special thermal reduction was proposed to synthesize nanostructured reduced graphene oxide (RGO) with abundant oxygen-containing functional groups. The resultant RGO showed high specific capacity and excellent cyclability as cathode materials for LIBs. The specific capacity of about 220 mAh g−1 at a current density of 50 mA g−1 was achieved after 100 cycles. More importantly, it was demonstrated that the capacity increased with the increase of the amount of oxygen functional groups, highlighting the significant effects of oxygen-containing functional groups of RGO on high lithium storage performance.

•The SnO2/GA nanocomposites were successfully synthesized via a hydrothermal method.•The performance of nanocomposite anodes highly depended on the hydrothermal time.•The 3-4 nm-sized SnO2/GAs showed enhanced cycling performance and rate performance.SnO2 has attracted intense interest for use as an anode material for lithium ion batteries because of various advantages of the high theoretical capacity and low-cost. Unfortunately, SnO2 anode material suffers from the huge volume change and poor electrical conductivity. In order to address these problems, in this work, SnO2/graphene aerogel composites have been successfully synthesized by a facile hydrothermal approach. 3-4 nm-sized SnO2 nanoparticles are uniformly dispersed over graphene aerogels. Our results indicate that the hydrothermal reaction time highly affects the electrode performance of the anodes. The nanocomposite electrode with reaction time of 3 h shows increased electrochemical performance with high energy capacity, long cycle life, and superior rate capability. After 100 cycles, it can deliver a high discharge capacity of 662 mAh g−1 at 100 mA g−1. At 500 mA g−1, it can still yield a discharge capacity of 619.7 mAh g−1 after 723 cycles. The performance improvement can attribute to the graphene aerogel, which can suppress the aggregation of SnO2 nanoparticles, enhance the conductivity of SnO2, and increase their structural stability during cycling. This study strongly demonstrates that the SnO2/graphene aerogel composite is a promising anode material building high performance lithium ion batteries.

•The 2D hierarchical ZnO nanoplates can be successfully fabricated via a facile sonochemical process.•The band-structure-matched hybrid ZnO-TiO2-SnO2 photoanodes were designed.•An overall power conversion efficiency of ∼6.37% was achieved for the SnO2@TiO2-ZnO nanoplates hybrid photoanodes with SnO2 blocking layer.The engineered interfacial and configuration design of anode materials plays pivotal role in photovoltaic performance of solar cells. Here we demonstrated a double layered SnO2@TiO2-ZnO nanoplates composite films on fluorine-doped tin oxide (FTO) substrate as photoanodes for high-performance dye-sensitized solar-cells (DSSCs). The results indicate that DSSCs based on double layered SnO2@TiO2-ZnO nanoplates composite film (∼5.55%) show an obvious 29.1% increase of power conversion efficiency as compared to the single layered SnO2@TiO2 nanoparticles photoelectrode with the same thickness of ∼18.5 μm. Intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) as well as electrochemical impedance spectra (EIS) measurements show that the double layered SnO2@TiO2-ZnO nanoplates film has faster electron transport rate and slower electron recombination rate than the SnO2@TiO2 one. Furthermore, final power conversion efficiency has been optimized to reach up ∼6.37% (Jsc of 17.18 mA cm−2, Voc of 742 mV and FF of 0.50) for the double layered SnO2@TiO2-ZnO nanoplates film photoanodes with the introduction of additional SnO2 blocking layer which would suppress the electron recombination between FTO glass and electrolyte. One of the specific advantages of the unique structure is the engineered integration of different promising materials, which made it possible to take full advantages of the superior dye adsorption, charge collection, charge transfer dynamics as well as optical scattering simultaneously. This study provides a scheme to selective combination of specific semiconductors metal oxides, namely, SnO2, TiO2 and ZnO, into an ideal photoanode configuration according to the feasible electron injection and transport dynamics, which has been regarded as promising photoanode materials for DSSCs. Fundamentally, this unique structure not only enables the high-efficiency solar cells application, but also provides a scheme for the inspiration of materials integration and guidance of effective materials surface and interfacial modification.

•The electrochemical reaction kinetics of the Ni/NiO anode was studied for the first time.•Charge transfer resistance is main contribution to total resistance during discharge process.•The slow growth of the SEI film is responsible for the capacity fading upon cycling.•Some promising strategies to optimize NiO anode performance were summarized.The electrochemical reaction kinetics of the porous core–shell structured Ni/NiO anode for Li ion battery application is systematically investigated by monitoring the electrochemical impedance evolution for the first time. The electrochemical impedance under prescribed condition is measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge (DOD) during charge–discharge cycles. The Nyquist plots of the binder-free porous Ni/NiO electrode are interpreted with a selective equivalent circuit composed of solution resistance, solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, and the surface configuration of the obtained electrode may experience significant change during the first two cycles. Meanwhile, the increase of internal resistance reduced the utilization efficiency of the active material may be another convincing factor to increase the irreversible capacity. In addition, the impedance evolution of the as-prepared electrode during charge–discharge cycles reveals that the slow growth of the SEI film is responsible for the capacity fading after long term cycling. As a result, several strategies are summarized to optimize the electrochemical performances of transition metal oxide anodes for lithium ion batteries.

•The SnO2 anode materials with various nanoparticle sizes were synthesized.•The particle size effects of SnO2 anodes on battery performance were studied.•The SnO2 nanoparticles with smaller size well buffer volume change upon cycling.•The small-sized anodes result in better electrochemical performance.The SnO2 anode materials with various nanoparticle sizes were successfully synthesized to study their size effects on lithium storage performance. The compositions, structures, particle sizes and morphologies of the as-prepared samples were characterized by X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) techniques. It was confirmed that the obtained nanomaterials via a facile reflux approach show smaller size than that of hydrothermal method. Using cyclic voltammograms, electrochemical impedance spectroscopy, and galvanostatical charge/discharge testing, the SnO2 anodes with different nanoparticle sizes exhibit various electrochemical performance with lithium, originating from the enormous volume changes associated with the alloying and de-alloying processes. It was demonstrated that the anode material with smaller nanoparticle size performs much better lithium storage performance.

•The SnO2–ZnO nanofibers are prepared via a simple electrospinning technology.•The composites show the uniform fiber like structure constituting of nanoparticles.•The SnO2–ZnO nanofibers show the enhanced properties than pure SnO2.•The influence of ZnO on the electrochemical performances has been discussed.The novel SnO2–ZnO nanofibers were successfully synthesized via a simple electrospinning technique. The influences of different amount of ZnO on the electrochemical properties have been discussed. Compared with SnO2 nanofibers, the SnO2–ZnO nanocomposites show the improved lithium storage capacity, cycling performance and rate properties. The beneficial effects can be attributed to the addition of ZnO nanoparticles, which can effectively buffer the volume exchange of SnO2 and create synergistic effects between them. Thus, as-prepared SnO2–ZnO nanofibers may hold great promise for the development of high-performance lithium ion batteries, and this work can be enlightening for material design and optimization.

Engineered metal oxide anode materials highly affect the photovoltaic performance of solar cells. In this research, we fabricate double-layered ZnO nanoarray (NR)/ellipsoid or sphere films on a fluorine-doped tin oxide (FTO) substrate as photoanodes for dye-sensitized solar cells (DSSCs). The results indicate that DSSCs based on the double-layered ZnO NR/sphere film (∼3.19%) show an obvious 41.2% enhancement of power conversion efficiency (PCE) compared to the ZnO NR/ellipsoid film (∼2.26%), which is confirmed by IMPS, IMVS, EIS and UV-vis diffuse reflectance studies. This study provides a scheme for the selective combination of specific ZnO morphologies into an ideal photoanode configuration with more dye loading and superior light scattering ability for enhanced photovoltaic performance.

•The films were prepared by multi-target magnetron co-sputtering.•The structure and properties were influenced obviously by substrate bias voltages.•Maximum hardness and modulus at −160 V were higher than monolithic films.•The film at −160 V also showed better thermostability and oxidation resistance.The nanocomposite Nb–B–Al–O films based on NbB2 and Al2O3 were successfully deposited on Si substrate via multi-target magnetron co-sputtering method. The influences of substrate bias on microstructure, mechanical, thermostability and oxidation resistance properties of the films were investigated in detail. Transmission Electron Microscopy (TEM), X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to study the structural properties such as crystallinity, binding energy and chemical composition of as-prepared films. The combination of monocrystalline NbB2 (1 0 0) texture and Al2O3 (1 1 3) crystal plane affected the mechanical properties of the films at different bias voltages. The best crystallization appeared at −160 V. The maximum hardness (23.4 GPa) and elastic modulus (274.5 GPa) of the films were obtained at optimal substrate bias of −160 V. The hardest film at −160 V also showed the better thermostability and oxidation resistance properties at 300 °C. This work also demonstrated that the decreased crystallinity induced at higher via voltage led to the decreasing in the mechanical properties.Graphical abstractNb–B–Al–O nanocomposite films were synthesized by multi-target magnetron co-sputtering. Different substrate bias voltages can influence properties of obtained nanocomposite films. The maximum hardness at −160 V bias also showed the better thermostability and oxidation resistance properties at 300 °C in the air. More significantly, the TEM images and XRD results of the nanocomposite films at different bias obviously interpreted the change in mechanical properties, which provides a powerful inspiration to better understand the strategies to improve these films’ engineering applications.

•Hierarchical porous vanadium pentoxide nanofibers were synthesized by electrospinning.•V2O5 nanofibers showed much enhanced lithium storage performance.•Kinetics process of electrospinning V2O5 nanofibers was studied by means of EIS for the first time.•Strategies to enhance the electrochemical performance of V2O5 electrode were concluded.The hierarchical V2O5 nanofibers cathode materials with diameter of 200–400 nm are successfully synthesized via an electrospinning followed by annealing. Powder X-ray diffraction (XRD) pattern confirms the formation of phase-pure product. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) obviously display the hierarchical porous nanofibers constructed by attached tiny vanadium oxide nanoplates. Electrochemical behavior of the as-prepared product is systematically studied using galvanostatic charge/discharge testing, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). It turns out that in comparison to the commercial V2O5 and other unique nanostructured materials in the literature, our V2O5 nanofibers show much enhanced lithium storage capacity, improved cyclic stability, and higher rate capability. After 100 cycles at a current density of 800 mA g−1, the specific capacity of the V2O5 nanofibers retain 133.9 mAh g−1, corresponding to high capacity retention of 96.05%. More importantly, the EIS at various discharge depths clearly reveal the kinetics process of the V2O5 cathode reaction with lithium. Based on our results, the possible approach to improve the specific capacity and rate capability of the V2O5 cathode material is proposed. It is expected that this study could accelerate the development of V2O5 cathode in rechargeable lithium ion batteries.

•Easy preparation method based on hydrothermal treatment.•Unique hierarchical porous structure with interconnected micro-, meso- and macroporous network.•Excellent electrochemical performances as capacitor electrode material.Three-dimensionally (3D) hierarchical porous carbon has been prepared through a simple and efficient hydrothermal treatment on colloidal silica as template. Nitrogen adsorption-desorption isotherms and transmission electron microscope images reveal that the porous carbon has a unique 3D interconnected micro-, meso- and macroporous network. The observed 3D interconnected meso/macroporous network originates from the cores of carbon hollow-spheres and the aggregation of crosslinked carbon hollow-spheres, and the micropores exist from the 3D interconnected network inside the shells of carbon hollow-spheres. The electrochemical capacitive tests indicate that the porous carbons exhibit large specific capacitance of about 300 F g−1 at 1 A g−1 in 6 M KOH aqueous electrolyte as well as high capacitance retention of 71% when the current density increased by 10 times.

•Small particle sizes TiO2–RGO from 5 nm to 20 nm in diameter.•Fast charge/discharge rate and high enhanced cycling performance.•A green synthetic route to produce the small particle nanocomposite of TiO2–RGO.A rutile and anatase mixed crystal phase of nano-rod TiO2 and TiO2–reduced graphene oxide (TiO2–RGO) nanocomposites with small particle size were prepared via a facile hydrothermal approach with titanium tetrabutoxide and graphene oxide as the precursor. Hydrolysis of titanium tetrabutoxide and mild reduction of graphene oxide were simultaneously carried out. Compared with traditional multistep methods, a novel green synthetic route to produce TiO2–RGO without toxic solvents or reducing agents was employed. TiO2–RGO as anode of lithium ion batteries was characterized by extensive measurements. The nanocomposites exhibited notable improvement in lithium ion insertion/extraction behavior compared with TiO2, indicating an initial irreversible capacity and a reversible capacity of 295.4 and 112.3 mA h g−1 for TiO2–RGO after 100 cycles at a high charge rate of 10 C. The enhanced electrochemical performance is attributed to increased conductivity in presence of reduced graphene oxide in TiO2–RGO, a rutile and anatase mixed crystal phase of nano-rod TiO2/GNS composites, small size of TiO2 particles in nanocomposites, and enlarged electrode–electrolyte contact area, leading to more electroactive sites in TiO2–RGO.

•LiPON solid-state electrolyte films are synthesized by IBAD.•18 mA contributes the highest hardness, lower stress and higher critical fracture.•18 mA beam current leads to same atomic percentage of N and P elements.•18 mA also contributes the an increase of Li-ion conductivities.•Desirable mechanical properties prevent LiPON films delamination from electrodes.Lithium phosphorus oxynitride (LiPON) solid-state electrolyte films were synthesized by ion beam assisted deposition (IBAD) system from Li3PO4 target in nitrogen reactive plasma. Extensive measurements were taken to investigate the change in structural characteristics caused by beam current as well as the effects on mechanical properties of LiPON films. The existence of the triply coordinated nitrogen atoms in structure of LiPON films induced by ion beam bombardment was proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which can produce the positive effects on Li+ mobility. Analysis of nanoindentation indicated that the hardness and elastic modulus of LiPON solid-state electrolyte films varies with the beam current. The highest hardness of 5.8 GPa and the highest critical fracture load of 3.01 mN with lower compressive stress occurred at equal atomic percentage of nitrogen and phosphorus, i.e. N/P = 1 at the beam current of 18 mA. The higher hardness and lower stress are important parameters to prevent LiPON solid-state electrolyte films delamination from electrodes, which is crucial in evaluating the electrochemical performance of thin-film lithium ion battery.

•LiPON electrolyte films were prepared by IBAD.•When FN2:FAr = 1:8, N atomic percentage attains a highest value of 2.32%.•The highest N content contributes the highest hardness and the lowest stress.•There is consistent variation in mechanical properties and ionic conductivities.•The highest ionic conductivity of 4.5 × 10−6 S/cm is achieved at FN2:FAr = 1:8.Lithium phosphorus oxynitride (LiPON) solid state amorphous film electrolytes were synthesized by ion beam assisted deposition (IBAD) using Li3PO4 target under nitrogen reactive plasma. IBAD presents an advantage of controllable nitrogen content of the films by adjusting N2 and Ar flow ratio. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), nanoindenter, and profiler were employed to characterize LiPON films. Our results indicate that the film at N2 and Ar flow ratio of 1:8 showed the best surface morphology and mechanical properties. The highest N atomic percentage of 2.32% was also obtained at this synthesis circumstance, and the resultant LiPON film electrolyte showed higher ionic conductivity of 4.5 × 10−6 S/cm at room temperature, as well as the highest hardness of 6.8 GPa and the lowest compressive stress of 147.2 MPa. It is believed that as-prepared LiPON solid state electrolyte film optimized can effectively prevent delamination from electrodes, showing some promising application in thin film lithium ion batteries.

•TiB2/c-BN interface is simulated and calculated using first-principles.•Twelve specific models are chose to simulate TiB2(0 0 1)/c-BN(1 1 1) interface.•TiB2(0 0 1)/c-BN(1 1 1) is the most stable interface among all interfaces.•The calculated parameters prove the strongest bonding of Ti–N at the interface.•The most stable interface supports measured results of TiB2/c-BN multilayers.A detailed theoretical investigation of the structural properties and thermodynamic stability of TiB2(0 0 1)/c-BN(1 1 1) interface was performed using first-principles calculations based on density functional theory. Twelve specific geometry models of the equilibrium atomic and electronic structures were chosen. The calculated interface energy suggested the most stable interface structure which yielded the lowest interface energy of −1.0 eV/Å2 had the Ti–N bonding across the interface. A particular analysis of the electronic structures including charge density distribution, layer-projected density of states and Mulliken population indicated that Ti–N interface had the strongest bonding combined polar covalent and ionic bonding.

•CIGS films were deposited by the one step RF magnetron sputtering.•CIGS films were prepared without a post-selenization process.•Different substrate temperatures were chosen during deposition.•580 °C is an optimal T to the smooth surface and large grain size of CIGS films.Cu(InxGa1 − x) Se2 (CIGS) thin films were deposited onto soda-lime glass substrates with Mo coating via the one step radio frequency (RF) magnetron sputtering without a post-selenization process at the substrate temperature varying from 550 °C to 630 °C. The effect of deposition temperature on the structural properties of CIGS thin films has been characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). It was found that an increased deposition temperature of up to 580 °C contributes to produce the smooth surface, large grain size, and increased crystallinity of the thin films. But further increased deposition temperature results in a decrease in smoothness and an increase in grain size. The optimized temperature (580 °C) shows the best effect on the composition and formation of the chalcopyrite structure without impurities.

Though multiwalled carbon nanotubes (MWCNTs) have shown great promise in biomedical applications, our understanding about their biocompatibility is limited. Here, COOH+ implantation was performed for MWCNTs in order to gain insight into how COOH+ implantation affected the cell growth and blood adsorption of MWCNTs. The extensive measurements demonstrated that carboxyl groups were successfully introduced onto the surface of MWCNTs, inducing more hydrophilicity compared with pristine MWCNTs. Two kinds of cells, mouse fibroblast cells (L929) and human endothelial cells (EAhy926), were used to assess the cell growth of MWCNTs before and after COOH+ implantation. COOH+ implantation led to a significant improvement in cell proliferation and adhesion, indicating superior cell adhesion over pristine MWCNTs. As the ion dose increased, the platelet adhesion assays of COOH+ implantation-MWCNTs (COOH/MWCNTs) displayed a significant enhancement, which implied COOH/MWCNTs could be used as anticoagulant and nonhemolytic material. The results were helpful to design modified surfaces of nanomaterials for improving their biocompatibility.

Nitrogen ion implanted graphene (N/graphene) was investigated for its interaction with mouse fibroblast cells, human endothelial cells and rabbit blood. The results showed that cells cultured on N/graphene displayed increased cell-viability, proliferation, and stretching when compared to those cultured on pristine graphene. An clinical acceptable hemolytic rate (below 5%) and lower platelet adhesion and prolonged kinetic blood-clotting time were also observed for N/graphene, indicating better thromboresistance than pristine graphene. Fourier transformer infrared spectrophotometry (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements proved that N ion implantation induced introduction of N element and appearance of NC functional groups on N/graphene. The polarity and electronegativity induced by N-containing functional groups on the N/graphene may be related to the improved cytocompatibility and hemocompatibility.

The purpose of this work is to detect the performance of carbon nanotubes with different nitrogen contents as anodes in lithium ion batteries. Carbon nanotubes with different nitrogen contents were synthesized by a floating catalyst chemical vapor deposition method. Melamine was employed as nitrogen precursor to effectively monitor nitrogen content in the nitrogen doped carbon nanotubes (CNx-NTs) and to modify their structures. X-ray photoelectron spectroscopy (XPS) was used to indicate the correlation between the nitrogen content and precursor amount. The study shows that with the increase of melamine amount, the growth rate of the tubes was enhanced and the diameter became bigger. Transmission electron microscopy (TEM) results demonstrated Bamboo-like structure of CNx-NTs. Investigation of their electrochemical properties as anodes for lithium ion batteries showed the discharge capacity of CNx-NTs anodes improved as their nitrogen concentration increased. Also, higher reversible capacities and better rate capabilities were observed. The superior electrochemical performance could be related to the high electrical conductivity and the larger number of defect sites. These performances revealed that the electrochemical activities of carbon nanotubes have been enhanced by the incorporation of nitrogen atoms.

Graphene is functionalized with amine by NH2 ion implantation at room temperature in vacuum. The reaction is featured by nucleophilic substitution of C–O groups by the ammonia radicals. The presence of N-containing functional groups in graphene is identified by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. N element was successfully introduced to graphene, the atomic ratio of N to C rose to 3.12 %. NH2 ion implanted graphene (G-NH2) is a better hydrophilic material than pristine grahene according to the contact angle experiment. Mouse fibroblast cells and human endothelial cells cultured on G-NH2 displayed superior cell-viability, proliferation and stretching over that on pristine graphene. Platelet adhesion, hemolysis and Kinetic-clotting time were measured on G-NH2, showing excellent anticoagulation, with as good hemolysis as pristine graphene.

TiAlN/TiB2 multilayers which have various modulation ratios (tTiAlN:tTiB2) ranging from 1:6 to 18:1 were synthesized on Al2O3(111) substrate by ion beam assistant deposition (IBAD). The effects of annealing on the mechanical and structural properties of the multilayers were investigated using X-ray diffractometry (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Nanoindenter (CSM instruments). It was found that the hardness for all multilayers was higher than TiAlN or TiB2 monolayer and the highest hardness of 43 GPa was attained at tTiAlN:tTiB2 = 16:1. The multilayers show the polycrystallines of TiAlN(111) and (220) textures. The thermal stability characteristics of the multilayers were studied in vacuum furnace for 30 min at temperatures of 500 and 700 °C. Compared with as-deposited multilayers, the annealed multilayers displayed a stable hardness and elastic modulus and an increased fracture resistance. It was found that the multilayers showed good thermal stability.Highlights► TiAlN/TiB2 multilayer is a candidate as protective coating in high temperature. ► Modulation ratio is key factor corresponding to its hardness and fracture resistance. ► Highest hardness of 43 GPa was attained at tTiAlN:tTiB2 = 16:1. ► Structure and properties kept thermal stability after annealing.

The multiwalled carbon nanotubes (MWCNTs) were prepared on SiO2 substrates using chemical vapor deposition (CVD). N ion beam bombardment to MWCNTs was performed at different beam currents of 5–15 mA in an ion-beam-assisted deposition (IBAD) system. Scanning electron microscope (SEM) and Transmission electron microscope (TEM) proved no significant crack and surface morphological change for MWCNTs after N ion beam bombardment. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FTIR), and Raman studies indicated that higher N ion beam current (15 mA) or N atomic concentration (8.6%) induced formation of polar N-containing functional groups of N–C and N–H bonds on the surfaces of MWCNTs. The content of N–C and N–H bonds increased with N ion beam current.

Nanostructured multilayers of TiB2/TiAlN at different modulation ratios (tTiB2:tTAlN) ranging from 1:24 to 6:1 were deposited onto Si(100) wafers by ion beam assisted deposition (IBAD). The multilayers were subsequently annealed in a vacuum environment at a temperature of 500 °C for 30 min, and then characterized by extensive measurements including X-ray reflection (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM), nano-indentation and surface profilometry. It was found that the mechanical properties of the multilayers were closely related to tTiB2:tTAlN. A maximum hardness of 37 GPa was achieved at tTiB2:tTAlN of 1:18 for as-deposited TiB2/TiAlN multilayer. This hardest multilayer also showed the improved residual stress and fracture resistance. The hardness and elastic modulus of the multilayers increased significantly after annealing. The maximum hardness of the multilayer at tTiB2:tTAlN of 1:14 was up to 41 GPa after annealing at 500 °C.Highlights► TiB2/TiAlN multilayer has potential on quality in protective coatings. ► Modulation ratio is a key factor corresponding to its mechanical properties. ► There is a critical modulation ratio for the hardest multilayer. ► Annealing at 500 °C gives a significant contribution to its properties.

TiAlN/Al2O3 multilayers which had different separate layer thickness of TiAlN or Al2O3 were synthesized by sputtering Ti3Al and Al2O3 targets with N2 and Ar gases. The influence of modulation periods and modulation ratios on structure and properties of TiAlN/Al2O3 multilayers was investigated using scanning electron microscopy, X-ray diffraction, X-ray Photoelectron Spectroscopy, surface profiler, and nanoindenter. Compared to TiAlN layer with only (2 0 0) preferred orientation, TiAlN/Al2O3 multilayers were crystallized with orientations in the TiAlN (1 1 1), TiAlN (2 2 2) and AlN (1 0 0). Besides, weak Al2O3 (0 2 2) orientation is observed, when modulation period is 8.9 nm. The maximum hardness about 36.6 GPa was obtained at modulation period of 10.4 nm and modulation ratio of 10:1. The hardness and the toughness of TiAlN/Al2O3 multilayers increase as individual TiAlN layer thickness increases.

Growth, structure, and mechanical properties of the nanocomposite Zr–Nb–N coatings deposited on Si(1 0 0) at different substrate bias voltages and substrate temperatures were performed by multi-target magnetron co-sputtering system. Extensive measurements were taken to investigate the influences of substrate bias voltage and deposition temperature on microstructure, hardness, elastic modulus, residual stress, critical fracture load. The maximum hardness and elastic modulus was up to 36 GPa and 425 GPa, respectively. The hardest coating also showed the lowest residual stress and the highest critical load. These enhancement effects should be related to nanocrystalline solid-solution microstructure formation and smaller grain size. These Zr–Nb–N coatings appeared to be a promising composite coating system suitable for engineering applications.

TiB2/BN multilayers with the modulation ratios (tTiB2:tBN) ranging from 1:1 to 16:1 and a constant modulation period of 24 nm were prepared by magnetron sputtering. The TiB2/BN multilayers were subsequently annealed in a vacuum environment at temperatures of 500–700 °C for 30 min, then characterized by extensive measurements. All multilayers exhibited small grain sizes and stable layer structures with polycrystalline with TiB2(001), TiB2(101), TiB2(002) textures or amorphous BN, resulting in higher hardness and elastic modulus than that of individual monolithic TiB2 or BN coatings. The hardness of as-deposited multilayer can reach as high as 39.34 GPa at tTiB2:tBN = 13:1, meanwhile the friction coefficient got to 0.028, which was also the lowest. The hardness and friction were almost unchanged after annealing at 500–700 °C, which was attributed to good thermal stability in the layer structure and the existence of stable TiBxNy phases.Highlights► TiB2/BN multilayers have potential as protective coating in dry machining. ► Annealing is found to be beneficial for thermal stability. ► The highest hardness of 39.34 GPa appears at tTiB2:tBN = 13:1. ► Good thermal stability of the properties of annealed layers is observed. ► Thermally stable TiBxNy phases contributes to stable layer structure and properties.

Carbon nitride (CNx) and diamond-like carbon (DLC) coatings were prepared by dc magnetron sputtering at room temperature. Different partial pressures of N2 were used to synthesize CNx to evaluate the relationship between the atomic percentage of nitrogen and hemocompatibility. Auger electron spectroscopy and atomic force microscopy indicated atomic percentages of N of 0.12 and 0.22 and that the CNx coatings were smooth. An in vitro study of the hemocompatibility of the coatings revealed that both CNx coatings had better anticoagulant properties and lower platelet adhesion than DLC. Compared with CN0.12, the CN0.22 coating showed longer dynamic clotting time (about 42 min), static clotting time (23.6 min) and recalcification time (45.6 s), as well as lower platelet adhesion (102 cells μm−2), aggregation, and activation. The presence of nitrogen in the CNx coatings induced their enhanced hemocompatibility compared with DLC.

Alternate hard TiAlN/TiB2 multilayers with different modulation periods (Λ) ranging from 0.6 to 27 nm and modulation ratios (tTiAlN:tTiB2) ranging from 8:1 to 25:1 were prepared using an ion beam assisted deposition (IBAD) system. The effect of Λ and tTiAlN:tTiB2 on the hardness, elastic modulus, residual stress, and fracture resistance were investigated using various characterization techniques. All multilayers with clear interfaces displayed higher hardness than individual TiAlN and TiB2 layers. The maximum hardness of 35 GPa and critical load of 84 mN were obtained for the multilayer with a Λ of 2.2–8.8 nm and tTiAlN:tTiB2 of 8:1. Strong TiAlN (111) crystallographic texture as well as multilayer structure is thought to be be responsible for the increasing hardness of the TiAlN/TiB2 multilayers.Highlights► TiAlN/TiB2 multilayer has potential on quality in protective coatings. ► Modulation period and ratio are related to its properties. ► A critical modulation period and ratio correspond to the hardest multilayer.

Dense nanocrystalline BaTiO3 ceramics with 50 nm average grain size obtained by spark plasma sintering were investigated. The dielectric data show a ferro-para phase transition with a maximum permittivity of 1602 at 120 °C and at 1 kHz. The polarization-reversal characteristics and the local ferroelectric switching behavior were measured; the typical piezoelectric hysteresis loops were recorded. The asymmetry of permanent polarization and coercive field in polarization–electric field curves were obtained and attributed to the existence of internal electric field. The present results provide experimental evidence, indicating that if a critical grain size exists for ferroelectricity it is less than 50 nm for polycrystalline BaTiO3 ceramics.

Monolithic ZrB2, W coatings and ZrB2/W multilayers with different modulation periods and modulation ratios were synthesized by ion beam assisted deposition at room temperature and 400°C. X-ray diffraction (XRD), scanning electron microscopy (SEM), surface profiler, and nanoindention were employed to investigate the influences of the deposition temperature and the modulation period on the growth, textures, interface structure, and mechanical properties of the multilayers. The results indicated that the multilayer with modulation period of 13 nm synthesized at room temperature possessed a higher hardness of 23.8 GPa. Deposition temperature gave a significant contribution to mechanical property enhancement. The 400°C-deposition temperature led to a maximum hardness and elastic modulus value of 32.1 and 399.1 GPa for ZrB2/W multilayer with a modulation period of 6.7 nm. Its critical load increased to 42.8 mN and residual stress decreased to −0.7 GPa. A higher deposition temperature can cause an increase in interfacial atomic mixture and mobility of surface species, which induceds an increase in areal atomic density and dislocation pinning. These results as well as small nanoscale grain sizes should be related to hardness increase.

AlN/ZrB2 multilayered coatings were synthesized in a magnetron sputtering system. The extensive measurements were employed to investigate the influence of different nanoscale modulation periods and modulation ratios on microstructure and mechanical properties of the coatings. Analysis of X-ray diffraction, profiler and nanoindention indicated that multilayered coatings possessed much higher hardness and elastic modulus than monolithic AlN and ZrB2 coatings. At the substrate negative bias of −80 V, maximum hardness (34.1 GPa) and elastic modulus (469.8 GPa) were obtained in the multilayer with Λ = 30 nm and tAlN:tZrB2 = 1:3. This hardest multilayer showed a marked polycrystalline structure with the strong mixture of ZrB2 (001), ZrB2 (100), ZrB2 (101), AlN (100) textures.

This article concerns the investigation of blood protein adsorption on carbon paper and multi-wall carbon nanotubes (MWCNTs). Mouse fibroblast cell adhesion and growth on MWCNTs was also studied. The results showed that fibrinogen adsorption on carbon paper was much lower than that on MWCNTs, which means that platelets readily aggregate on the surface of MWCNTs. Mouse fibroblast cells implanted on MWCNTs tended to grow more prolifically than those implanted on carbon paper. The cell concentration observed on MWCNTs increased from 1.2×105/mL for a single day culture to 2×105/mL for a 7-day culture. No toxicity reaction was observed during the culturing period. These results indicated that MWCNTs possessed excellent tissue compatibility.

TiB2/TiAlN multilayered coatings with various modulation ratios (tTiB2:tTiAlN) were grown using radio-frequency magnetron sputtering at room temperature. Nanoindentation, tester for material surface properties, and XRD were used to investigate the influence of modulation ratio on microstructure and properties of the multilayers. All multilayers showed improved mechanical properties, compared with the average value of the monolithic TiB2 and TiAlN coatings. The multilayer with modulation ratio of 5:2 displayed the highest hardness (36 GPa) and longest time to crack during wear. A marked layer structure with the strong mixture of TiAlN (111), AlN (111), and TiB2 (001) textures with smaller grain sizes was responsible for the enhanced hardness.

ZrN/W multilayered coatings with different modulation periods at the nanoscale were synthesized at different N+ beam bombarding energies using ion beam assisted deposition. The coatings were subsequently annealed at 700 °C for 1 h, followed by characterization using XRD, AES, and nanoindentation. All multilayers revealed higher hardness than the average value of the monolithic ZrN and W coatings. This behavior and structure indicated a good thermal stability after annealing. A marked layer structure with the strong mixture of ZrN (111) and W (110) textures was responsible for the enhanced hardness.

ZrN/W multilayered coatings with different modulation periods at the nanoscale have been synthesized at different N+ beam bombarding energies using IBAD. Various characterization techniques such as XRD, AES, nano indenter and profiler were employed to investigate the influence of modulation period and bombarding energy on microstructure and mechanical properties of the coatings. The results showed that all superlattice coatings had better mechanical properties than the monolithic ZrN and W coatings. At an optimal condition with 300 eV N+ beam bombarding energy and 8–9 nm modulation period, XRD pattern possessed a significantly structural mixture of strong ZrN (111), W (110), as well as weak ZrN (220) textures in the multilayered coating. The optimal condition resulted in higher hardness (26 GPa), elastic modulus (310 GPa) and fracture resistance of the coating than other conditions.

Multilayered gradient CrN/ZrN coatings were synthesized by a dual cathode dc magnetron sputtering. The influence of species of reaction gases and partial pressures on structural and mechanical properties was explored. Both nanoindentation and nanoscratch fracture tests showed that multilayered gradient coatings possessed much higher hardness and fracture resistance than monolithic ZrN and CrN coatings. A proper percent of NH3 in N2 reaction gas was proved to be of benefit to the synthesis of high hardness and fracture-resistant CrN/ZrN coatings with strong adhesion to substrate. The hardness and critical fracture load exceed 55 GPa and 100 mN, respectively. The multilayered gradient structure with strongly mixed CrN(111), Cr2N(112), ZrN(111), and ZrN(220) orientations is responsible for the enhanced mechanical properties.

Ultrathin CNx overcoats were grown using pulsed dc magnetron sputtering. Substrates were mounted on a holder that allowed 45° tilt angle and rotation. Effects of process parameters on film growth were reviewed. AFM scans over large sampling areas show that thin CNx films obtained at − 100 V substrate bias with 45° substrate tilt and 20–25 rpm rotation have r.m.s. roughness about 0.2–0.3 nm when sampled over 20 × 20 μm2 areas, increasing to ∼ 0.45 nm when sampled over ∼ 0.05 × 3 cm2 using X-ray reflectivity measurements. These 1–2 nm thick ultrasmooth coatings reduced corrosion damage compared with coatings of the same thickness grown without substrate tilt and rotation. This improved performance is likely a result of more efficient and uniform momentum transfer parallel to the surface during deposition in this configuration. In addition, detailed X-ray reflectivity measurements showed that the mass density of these CNx films is ∼ 2.0 g/cm3, independent of film thickness from ∼ 1 to 10 nm, consistent with ion beam analysis.

Cell attachment on the polymethylmethacrylate (PMMA) intraocular lens (IOL) was studied by ion implantation. F+ ion implantation was performed at an energy of 80 keV with fluences ranging from 5×1012 to 5×1015 ions/cm2 at room temperature. The cell attachment tests gave interesting results in that the number of the platelets, the neutral granulocytes, and the macrophages adhering on the surface of the IOLs was reduced significantly after F+ ion implantation. The optimal fluence was about 3×1014 to 4×1014 ions/cm2. The hydrophobicity imparted to the surface was also monitored. At the same time, no appreciable change in the tensile strength and the optical transmittance of the implanted samples was observed. X-ray photoelectron spectroscopy (XPS) and fourier transfer infrared (FTIR) analysis showed that F+ ion implantation caused the cleavage of some pendants, the oxidation of the surface, and the formation of some new F-containing groups. These results were responsible for the cell attachment changes.

Monolithic ZrB2, AlN, and ZrB2/AlN multilayered coatings have been synthesized by ion beam assisted deposition at room temperature. Scanning electron microscopy, X-ray diffraction, XP-2 profiler and nano indenter were employed to investigate the influences of modulation period and N + bombarding energy on microstructure and mechanical properties of the coatings. Most of multilayered coatings revealed higher hardness and elastic modulus than the rule-of-mixtures value of monolithic ZrB2 and AlN coatings. N + bombardment at 300 eV resulted in ZrB2/AlN multilayered coating the highest hardness (31.2 GPa) and elastic modulus (372.2 GPa). This hardest multilayer also showed the improved residual stress and fracture resistance. These improved performances are likely a result of more efficient momentum transfer to the deposition particles due to the proper N + bombarding energy.

Nanoscale W/ZrB2 multilayered coatings were prepared by rf magnetron sputtering system at room temperature. SEM, XRD, surface profiler and nano-indenter were employed to investigate the influences of modulation period (Λ) on the microstructure and mechanical properties of the films. The results showed that nanoscaled coatings had clear multilayered structure and almost all of multilayered coatings possess higher hardness and elastic modulus than the rule-of-mixtures value of monolithic W and ZrB2 coatings. At Λ=30 nm, W/ZrB2 multilayered with mixed polycrystalline texture exhibited the highest hardness of 41.5 GPa with lower residual stress.

The poriferous reduced graphene oxide (rGO) with abundant oxygen-containing functional groups synthesized by a one-step hydrothermal method was successfully employed as a high performance cathode in lithium-ion batteries. The electrochemical results show that the rGO exhibits a remarkable lithium storage capacity (up to 270 mA h g−1 after 100 cycles). Further analysis shows that the rGO can exhibit a significantly high rate capacity, good reversibility, and excellent cycling stability, which clearly reveals the potential use of the rGO as the cathode material to boost both energy and power densities of LIBs. Furthermore, by controlling the oxygenic functional groups of the rGO, it was demonstrated that the capacity of rGO increased with the increase of the number of oxygenic functional groups, which illustrates that the excellent electrochemical performance of rGO could be attributed to its specific poriferous structure and the oxygen-containing functional groups.

Though multiwalled carbon nanotubes (MWCNTs) have shown great promise in biomedical applications, our understanding about their biocompatibility is limited. Here, COOH+ implantation was performed for MWCNTs in order to gain insight into how COOH+ implantation affected the cell growth and blood adsorption of MWCNTs. The extensive measurements demonstrated that carboxyl groups were successfully introduced onto the surface of MWCNTs, inducing more hydrophilicity compared with pristine MWCNTs. Two kinds of cells, mouse fibroblast cells (L929) and human endothelial cells (EAhy926), were used to assess the cell growth of MWCNTs before and after COOH+ implantation. COOH+ implantation led to a significant improvement in cell proliferation and adhesion, indicating superior cell adhesion over pristine MWCNTs. As the ion dose increased, the platelet adhesion assays of COOH+ implantation-MWCNTs (COOH/MWCNTs) displayed a significant enhancement, which implied COOH/MWCNTs could be used as anticoagulant and nonhemolytic material. The results were helpful to design modified surfaces of nanomaterials for improving their biocompatibility.