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Micro-arc oxidation (MAO) was used to fabricate light-red coatings with a maximum Cu amount of 3.06 wt% on Ti-6Al-4V alloys in electrolytes composed of Na 2 CuY, KOH, and phytic acid. The influences of electrolyte composition and concentration as well as the electrical control mode on coating properties were investigated. In addition, the cathode surface after MAO treatment was first characterized. The results show that the used electrolytes determine the coating composition and surface morphology through influencing the solution pH and conductivity. During MAO, copper is simultaneously involved in the formation of the MAO coating on the anode and the precipitation of metallic Cu on the cathode. The copper content in MAO coatings can be improved slightly by Na 2 CuY and significantly by KOH attributed to their influences on solution pH . Phytic acid is beneficial in developing MAO coatings, but at higher concentrations up to 4 g/L decreases the copper content. The copper in MAO coatings exists primarily in the form of Cu 2 O, while metallic copper particles in the range of 150–600 nm are deposited on the cathode through the reduction reaction. Compared with the constant current density mode, the fabricated MAO samples under the constant voltage mode contain a lower content of Cu and more evident microcracks.

The developed micro-arc oxidation (MAO) coatings with good corrosion resistance and high calcium content are desirable for medical magnesium alloys. In this study, the influences of NaOH, sodium phytate (Na12Phy), Ca(H2PO4)2·H2O and treatment duration on corrosion resistance and calcium content of MAO coatings were systematically investigated using an orthogonal experiment of four factors with three levels. It is found that the corrosion resistance of MAO treated samples is synergistically determined by coating characteristics, though the developed microcrack and the coating roughness play a main role. The prolonged treatment duration or excessively high concentrations of NaOH and Na12Phy decrease the coating corrosion resistance due to intensive spark discharges and the subsequent development of microcracks on coating surface. The increased NaOH concentration has a negative impact on the calcium amount due to the improved solution pH value and the decreased Ca(H2PO4)2·H2O solubility in water solution. Proper Na12Phy is beneficial to improving the calcium amount attributed to the chelating reaction between Na12Phy and calcium ions. The increased Ca(H2PO4)2·H2O concentration and prolonged treatment duration improve the calcium content in MAO coatings, demonstrating that calcium ions enter into MAO coatings by both diffusion and electromigration.

As a kind of excellent structure, nanotubes are combined with the advantages of the hollow structure and one-dimensional structure. Especially, the metal oxide nanotubes have broad application prospects in the field of energy storage and conversion. In this paper, we design a simple method to synthesize 12 kinds of carbon-coated tube-in-tube composite nanofibers (TiTCNFs) via a single-spinneret green electrospinning and subsequent pyrolysis processes, including carbon-coated metal TiTCNFs (Ni@C), carbon-coated single metal oxides TiTCNFs (Fe3O4@C, NiO@C, Co3O4@C, Mn3O4@C, CuO@C) and carbon-coated binary metal oxides TiTCNFs (CoFe2O4, CoMn2O4, MnFe2O4, NiCo2O4, NiFe2O4, NiMn2O4). The carbon-coated metal oxides TiTCNFs have superior electrochemical performances in Li-ion batteries and supercapacitors compared with hollow nanotube and pea-like structured composite nanofibers. The good electrochemical performances of TiTCNFs ascribe to the moderate carbon content, large specific surface area, and unique tube-in-tube structure effectively relieving the volume effect during the cycling process. The design and synthetic strategy is available for fabricating a wide variety of carbon-coated metal oxide nanotubes.

Theranostics nanoplatforms offer opportunities for imaging-guided precision therapy and hold great potential for clinical applications. In most reported works, the imaging unit has a lack of site selectivity, and is always kept in the "on" modality regardless of whether it is in normal tissues or tumor sites, increasing the risk of unsafe treatment. Herein, we designed a near-infrared (NIR) fluorescence-guided theranostics nanoplatform by integrating the functions of tumor-response and photodynamic therapy (PDT)/photothermal therapy (PTT). A novel NIR fluorescent dye, CyPT, with excellent optical and PDT/PTT properties, was synthesized and linked onto the gold nanorods (AuNRs) to form CyPT-AuNRs nanohybrids via a sulfur-sulfur bond that can be broken by glutathione (GSH) with high selectivity and sensitivity. In normal cells where the concentration of GSH is low, the fluorescence of CyPT is quenched by the AuNRs. By contrast, the high level of GSH in tumor cells leads to the breaking of the sulfur-sulfur bond, resulting in the release of CyPT and the accomplishment of a "off-on" fluorescence response. Followed by precise NIR tumor-imaging diagnosis, the PDT and PTT treatment which rely on the released CyPT and AuNRs, respectively, can be effectively performed. The CyPT-AuNRs nanoplatform has been successfully applied to the treatment of tumor xenograft models and no distinct damage has been observed in the nearby normal tissues. This versatile nanoplatform has potential for use in targeted tumor imaging and precision therapy.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are effective cancer treatments, and photosensitizers play the most important role in the treatment. However, photosensitizers are insufficient for in vivo tumor treatment. Herein, we develop a small molecule fluorophore Cy-HPT as a novel photosensitizer, which possesses the advantages of near-infrared (NIR) emission, high photothermal conversion efficiency and high singlet oxygen generation efficiency. Moreover, a nanoplatform of HSA@Cy-HPT was synthesized by self-assembly of Cy-HPT and human serum albumin (HSA) in aqueous solution. Compared to Cy-HPT, HSA@Cy-HPT possesses more stable spectral properties, enhances the effect of PDT/PTT, and exhibits more satisfactory in vivo metabolism. HSA@Cy-HPT demonstrates outstanding tumor targeting in subcutaneous tumor xenograft models owing to its enhanced permeability and retention in tumor tissue. Furthermore, HSA@Cy-HPT was successfully utilized in tumor xenograft models and tumor tissue growth was clearly inhibited without any regrowth, extending survival rate of the models. Also, no distinct damage of the normal tissue of tumor xenograft models was observed using hematoxylin & eosin staining. This study presents a promising therapeutic agent for the synergetic PDT and PTT cancer treatment.

In this paper, multi-wall carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs) and thiolated calix[8]arene (TC8A) make a significant combination to fabricate TC8A/AuNPs/MWCNTs modified glassy carbon electrode (GCE), named as TC8A/AuNPs/MWCNTs/GCE, for the determination of paracetamol (PCM). During the preparation process of modified electrode, AuNPs are firstly in-situ growth on the MWCNTs/GCE by electrochemical deposition. Then, TC8A can self-assemble onto the surface of AuNPs through thiol groups to form ternary hybrid composite film TC8A/AuNPs/MWCNTs. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements show that the TC8A/AuNPs/MWCNTs/GCE modified electrode exhibits the good electrocatalytic activity and the high electrochemical response toward PCM. TC8A/AuNPs/MWCNTs/GCE modified electrode displays an excellent electrochemical performance for PCM by DPV with high current density of 7.64 mA mM−1 cm−2, broad linear range (1–150 μM) and low detection limit (0.2 μM) at a signal-to-noise ratio of 3. This superior performance is attributed to the synergic electrocatalytic effect of MWCNTs and AuNPs, and the enrichment capability of TC8A for PCM.

There exists great interest in the development of coatings that can simultaneously improve corrosion resistance and contain essential trace elements on biomedical magnesium alloys. In an alkaline solution composed of NaF, phytic acid (H12Phy), Na2SiO3 and EDTA-ZnNa2, it was demonstrated that zinc-containing coatings with improved corrosion resistance were successfully fabricated on WE43 magnesium alloys using a one-step micro-arc oxidation (MAO) procedure. The influences of Na2SiO3 and EDTA-ZnNa2 concentrations on MAO coating properties were systematically evaluated using SEM, EDS, XRD, XPS, scratch test and potentiodynamic polarization. These results demonstrate that MAO coatings containing 1.67 wt% Zn exhibit superior corrosion resistance. Na2SiO3 is one type of passive agent of magnesium alloys, and has been shown to be favorable for the formation of coatings as it enhances corrosion resistance by improving surface uniformity, coating thickness and adhesion to the substrate. Raised EDTA-ZnNa2 in the range of 1 to 3 g/L is found to increase zinc content in MAO coatings but decrease their corrosion resistance. As an acidic substance, EDTA-ZnNa2 is a corrosive agent of magnesium alloys and has shown to be harmful for the formation of MAO coatings. Additionally, the corrosion mechanism of MAO coatings was discussed by measuring electrochemical impedance spectroscopy as a function of immersion time.

Double-shell CeO2:Yb,Er@SiO2@Ag upconversion composite nanofibers are synthesized by electrospinning and subsequent process. CeO2:Yb,Er@SiO2@Ag nanofibers show high upconversion luminescence property due to the coating of amorphous SiO2 and the surface plasmon resonance effect of Ag nanoparticles. CeO2:Yb,Er@SiO2@Ag nanofibers act as an assistant layer in dye-sensitized solar cells (DSSCs) and enhance the photoelectric conversion efficiency (PCE) to 8.17%. The photocurrent-voltage characteristic is obtained under 980 nm laser as illumination light source. In addition, the absorption of the incident photon-to-current conversion efficiency curve in 900–1000 nm near-infrared light confirms that the introduction of the upconversion nanomaterial broadens the absorption range, improves the utilization rate of the sunlight and increases the PCE of DSSCs.

Bimetallic gold core-silver shell (Au@Ag) surface-enhanced Raman scattering (SERS) tags draw broad interest in the fields of biological and environmental analysis. In reported tags, silver coating tended to smooth the surface and merge the original hotspot of Au cores, which was disadvantageous to signal enhancement from the aspect of surface topography. Herein, we developed gold nanorod (AuNR)-bridged Au@Ag SERS tags with uniform three-dimensional (3D) topography for the first time. This unique structure was achieved by selecting waxberry-like Au nanoparticles (NPs) as cores, which were capped by vertically oriented AuNR arrays. Upon selective surface blocking with thiol-ligands, Ag NPs were controlled to anisotropically grow on the tips of the AuNRs, producing high-density homo- (Ag-Ag) and hetero- (Au-Ag) hotspots in a single NP. The 3D hotspots rendered this NP extraordinary SERS enhancement ability (an analytical enhancement factor of 3.4 × 106) 30 times higher than the counterpart with a smooth surface, realizing signal detection from a single NP. More importantly, multiplexing signals ("blank" or multiplex "internal standard") can be achieved by simply changing thiol-ligands, as exemplified in the synthesis of NPs with 8 signatures. Furthermore, the multifunctionality has been demonstrated in living cell/in vivo imaging, photothermal therapy, and SERS substrates for ratiometric quantitative analysis, relying on the inherent internal standard signal. The prepared Au@Ag NPs have great potential as standard tools in many SERS-related fields.

Fluoride doping Li4Ti5O12 nanosheets (F-LTO NSs) are synthesized using a facile hydrothermal reaction, followed by a calcination treatment. It is found that F atoms can enter the lattice structure of spinel LTO NSs without morphology change. Electrochemical test results shows that the fluoride doping of LTO NSs not only increased the electron conductivity of LTO NSs through trivalent titanium (Ti3+) generation, but also increased the robustness of the structure to repeated lithiation and delithiation. The rate performance of LTO NSs has been evidently improved by F doping. At the highest rate of 5 A g−1 (28.6C), F-LTO NSs still display a capacity retention of 101.4 mA h g−1. F-LTO NSs show superior cycling performance with the high reversible capacity at a current density of 2 A g−1 (11.4C), retaining 84.2% of its initial capacity after 1000 cycles with a capacity retention of 116.8 mA h g−1.

Double-shell SnO2/CeO2:Yb,Er hollow nanospheres (HNSs) are prepared using SiO2 as a template. Firstly, CeO2:Yb,Er nanoparticles (NPs) were coated on the surface of SiO2 to generate core–shell SiO2@CeO2:Yb,Er nanospheres. Then the SiO2 cores were removed accompanied by SnO2 deposition to form heterogeneous double-shell SnO2/CeO2:Yb,Er HNSs during a hydrothermal process. It can be seen from the structure analysis that the deposition of the SnO2 shell as the framework supports the CeO2:Yb,Er shell. When SnO2/CeO2:Yb,Er HNSs act as an assistant layer in dye-sensitized solar cells (DSSCs), the photoelectric conversion efficiency (PCE) is enhanced to 8.66%. Open-circuit voltage decay confirms that the lifetime of photogenerated electrons in the cells is prolonged. Double-shell SnO2/CeO2:Yb,Er HNSs might efficiently suppress the recombination of photoproduced electrons–holes, extend the electron lifetime, and further improve the photoelectric conversion performance of DSSCs.

Ultrathin WS2 nanosheets are vertically embedded in hollow mesoporous carbon spheres (HMCSs) to form unique hierarchical triple-shell (WS2–C–WS2) hollow nanospheres, i.e. HTSHNs WS2/C, via a facile and scalable hydrothermal method. The as-synthesized HTSHNs WS2/C nanocomposites are confirmed to have an expanded interlayer spacing of WS2 with chemical bonding between WS2 and HMCSs. The expanded WS2 interlayer spacing contributes to the enhancement of the kinetics of ion/electron transport and the improvement of the electrochemical performance of the HTSHNs WS2/C. As a result, the optimized HTSHNs WS2/C composites deliver a superior rate capability of 396 mA h g−1 at 10 A g−1, and stable cycling performance up to 1000 cycles, presenting a capacity of 784 and 442 mA h g−1 at 1 and 5 A g−1, respectively. Additionally, HTSHNs WS2/C provide abundant catalytically active sites for the enhancement of the electrocatalytic activity for the hydrogen evolution reaction (HER).

In this study, graphene nanosheets (GN) were modified by three ester-calix[n]arenes (ECnA, n = 4, 6, 8) using a simple self-assembly strategy. Three obtained ECnA/GN nanocomposites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscope and electrochemical impedance spectroscopy, which confirmed that the various amount of ECnA molecules had been effectively loaded onto the surface of GN. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements showed that the ECnA/GN modified electrodes exhibited high supramolecular recognition and enrichment capability and consequently displayed high electrochemical response toward dopamine (DA). At low concentration of guest molecule, the ECnA/GN modified electrodes show the better enrichment performances. Especially, EC8A/GN modified electrode exhibited an excellent electrochemical performance for DA with high current densities of 4.46 mA mmol − 1 L cm − 2 , broad linear range (0.5 to 400 μM) and low detection limit (0.2 μM) at a signal-to-noise ratio of 3.

Freestanding binder-free electrodes, as a new generation of electrode material, can effectively improve the energy density of lithium-ion batteries (LIBs). In this paper, novel structured Fe 3 O 4 /C composite nanofibers are successful synthesized by a simple electrospinning method followed by a thermal treatment process. The composite nanofibers have the unique internal voids between Fe 3 O 4 nanoparticles and carbon matrix. The Fe 3 O 4 /C nanofibers film with good flexibility and excellent electrical conductivity can be directly used to fabricate half-cell without any current collector, binder and additional conductive agent. As anode material for LIBs, the Fe 3 O 4 /C composite nanofibers deliver high reversible capacity (762 mA h g −1 at 0.5 A g −1 after 300 cycles). The results show that the internal voids in flexible Fe 3 O 4 /C composite nanofibers effectively buffer volume expansion of Fe 3 O 4 in lithium ion intercalation/deintercalation process and avoid the fracture of the nanofibers, which retain the structural integrity and improve the cycling stability of electrode. Therefore, the design and synthesis strategy of flexible nanofibers film are prospective for applications in next-generation flexible LIBs.

An innovative approach for efficient synthesis of petal-like molybdenum disulfide nanosheets inside hollow mesoporous carbon spheres (HMCSs), the yolk–shell structured MoS2@C, has been developed. HMCSs effectively control and confine in situ growth of MoS2 nanosheets and significantly improve the conductivity and structural stability of the hybrid material. The yolk–shell structured MoS2@C is proven to achieve high reversible capacity (993 mA h g–1 at 1 A g–1 after 200 cycles), superior rate capability (595 mA h g–1 at a current density of 10 A g–1), and excellent cycle performance (962 mA h g–1 at 1 A g–1 after 1000 cycles and 624 mA h g–1 at 5 A g–1 after 400 cycles) when evaluated as an anode material for lithium-ion batteries. This superior performance is attributed to the yolk–shell structure with conductive mesoporous carbon as the shell and the stack of two-dimensional MoS2 nanosheets as the yolk.

Among the numerous candidate materials for lithium ion batteries, ferroferric oxide (Fe3O4) has been extensively concerned as a prospective anode material because of its high theoretical specific capacity, abundant resources, low cost, and nontoxicity. Here, we designed and fabricated a unique yolk–shell construction by generating heterogeneous double-shelled SnO2 and nitrogen-doped carbon on Fe3O4 yolk (denoted as Fe3O4@SnO2@C–N nanoboxes). The yolk–shell structured Fe3O4@SnO2@C–N nanoboxes have the adjustable void space, which permits the free expansion of Fe3O4 yolks without breaking the double shells during the lithiation/delithiation processes, avoiding the structural pulverization. Moreover, the heterogeneous double-shelled SnO2@C–N can meaningfully improve the electronic conductivity and enhance the lithium storage performance. Two metal oxides also show the specific synergistic effect, promoting the electrochemistry reaction. As a result, this yolk–shell structured Fe3O4@SnO2@C–N exhibits high spe...

In this paper nitrogen-doped carbon-encapsulation Fe3O4 yolk−shell magnetic nanocapsules (Fe3O4@C-N nanocapsules) have been successfully constructed though a facile hydrothermal method and subsequent annealing process. Fe3O4 nanoparticles are completely enclosed in nitrogen-doped carbon shells with void space between the nanoparticle and the shell. The yolk−shell structure allows Fe3O4 nanoparticles to expand freely without breaking the outer carbon shell during the lithiation/delithiation processes. The volume expansion of Fe3O4 results in the in-depth nanocrystallization. Fortunately, the new generated small nanoparticles can increase the capability with the cycle increase due to the unique confinement effect and excellent electronic conductivity of the nitrogen-doped carbon shells. Hence, after 150 cycles, the discharge capacity of Fe3O4@C-N-700 nanocapsules still remained 832 mA h g−1 at 500 mA g−1, which corresponds to 116.7% of the lowest capacity (713 mA h g−1) at the 16th cycle. We believe that the yolk−shell structure is conducive to enhance the capacity of easy pulverization metal oxidation during the charge/discharge processes.

Yb,Er-doped CeO 2 nanotubes were successfully synthesized using Ag nanowires as a hard template via a facile hydrothermal reaction and subsequent calcination and leaching processes. Yb,Er-doped CeO 2 nanotubes as a promising assistant layer were investigated to determine theirs photovoltaic properties in an effort to enhance the power conversion efficiency of dye-sensitized solar cells (DSSCs). The influence factors of photoelectric properties of CeO 2 :Yb,Er NTs, including diameter of nanotubes, hydrothermal time, calcination temperature, and elements doping, have been studied. Compared with pristine P25 photoanode, the DSSCs fabricated by CeO 2 :Yb,Er nanotubes and P25 exhibited a power conversion efficiency ( η ) of 8.67%, an increase of 34%, and incident photo-to-electric conversion efficiency (IPCE) of 92.96%, an increase of 48.83%, which evidence that CeO 2 :Yb,Er NTs are a promising assistant photoanode material for DSSCs. The enhance mechanism of CeO 2 :Yb,Er nanotubes has been further revealed according to experimental results.

In this study, the synergistic effects of NH4HF2, sodium phytate (Na12Phy), K2ZrF6, and treatment time on corrosion resistance of a micro-arc oxidation (MAO) treated magnesium alloy and the entrance mechanism of P, F, and Zr into anodic coatings were investigated using an orthogonal method. In addition, the roles of NH4HF2, Na12Phy, and K2ZrF6 on coating development were separately studied. The results show that NH4HF2 and Na12Phy, the corrosion inhibitors of magnesium alloys, are beneficial but K2ZrF6 is harmful to developing anodic coatings. The corrosion resistance of MAO coatings is synergistically determined by coating characteristics, though the coating thickness plays a main role. Na12Phy significantly improves but NH4HF2 decreases the corrosion resistance of MAO coatings, while excess high K2ZrF6 is harmful to the coating corrosion resistance. Treatment time can increase the coating thickness but is the least important factor in corrosion resistance. During MAO, NH4HF2, Na12Phy, and K2ZrF6 take part in coating formation, causing P, F, and Zr to compete with each other to enter into anodic coatings.

Iron (Fe) is an important trace element for life and plays vital functions in maintaining human health. In order to simultaneously endow magnesium alloy with good degradation resistance, improved cytocompatibility, and the proper Fe amount for the body accompanied with degradation of Mg alloy, Fe-containing ceramic coatings were fabricated on WE43 Mg alloy by micro-arc oxidation (MAO) in a nearly neutral pH solution with added 0, 6, 12, and 18 g/L ferric sodium ethylenediaminetetraacetate (NaFeY). The results show that compared with the bare Mg alloy, the MAO samples with developed Fe-containing ceramic coatings significantly improve the degradation resistance and in vitro cytocompatibility. Fe in anodic coatings is mainly present as Fe2O3. The increased NaFeY concentration favorably contributes to the enhancement of Fe content but is harmful to the degradation resistance of MAO coatings. Our study reveals that the developed Fe-containing MAO coating on Mg alloy exhibits potential in clinical applications.

Nitrogen-doped mesoporous hollow carbon nanoflowers (N-HCNF) are successfully prepared by a facile hard-template route via a hydrothermal process, subsequent carbonization and etching. The as-synthesized N-HCNF has high specific surface area (507.5 m2 g−1) and unique nanostructure, which make N-HCNF a potential anode material for lithium ion batteries. In the electrochemical test, the as-prepared N-HCNF exhibit high specific capacity, markedly improve cycle stability, and enhance rate performance compared with nitrogen-doped hollow carbon nanorods (N-HCNR) and hollow carbon nanoflowers (HCNF). The as-prepared N-HCNF displays a reversible specific capacity of 528 mA h g−1 after 1000 cycles at 2C. N-HCNF shows the excellent rate performance and the stable capacity of N-HCNF maintains 298 mA h g−1 at 10C. The significant electrochemical property improvements of N-HCNF are attributed to the large BET surface area, N-doped carbon shell and unique 3D hollow nanostructure of N-HCNF.

The bimetallic sulfides with unique catalytic ability are highly attractive in energy conversion field. Herein, Co8FeS8/N–C dodecahedral nanocages (DNCs) are synthesized by ZIF-67 as a template through subsequent sulfidation and cation exchange strategy. Co8FeS8/N–C DNCs are fabricated by Co8FeS8 nanoparticles with superior crystallinity, which are coated with the N-doped carbon shell derived from organic ligands in ZIF-67. When Co8FeS8/N–C DNCs are applied as an efficient and low-cost Pt-free counter electrode (CE) for the dye-sensitized solar cells, they achieve a high power conversion efficiency (PCE) of 8.06%. The electrochemical results show that Co8FeS8 DNCs exhibit the best electrocatalytic activity for the reduction of triiodide (the smallest peak-to-peak separation and electron transfer impedance) than those of Pt counter electrode and monometallic sulfide Co9S8/N–C counter electrode.

Calcium phosphate (Ca-P) coatings were fabricated by micro-arc oxidation (MAO) on AZ31B magnesium alloy in near-neutral pH solutions (pH 7.6–7.9) and the influences of EDTA-CaNa2, phytic acid (IP6), phosphoric acid (PA), and treatment time on coating properties were investigated by an orthogonal experiment. The results show that coating corrosion resistance is synergistically determined by coating characteristics with coating thickness playing a particularly important role. EDTA-CaNa2 acts as a corrosive agent of magnesium alloys and the increased concentration increases calcium content but decreases corrosion resistance of MAO coatings. As a strong chelating agent, IP6 can promote EDTA-CaNa2 solubility and therefore increases the calcium content more effectively than PA does. Compared with PA, IP6 more effectively improves corrosion resistance mainly by increasing coating thickness and bonding strength between coating and substrate, although the uniformity of anodic coatings becomes worse due to the greater interfacial tension of the IP6 solution than that of the PA solution. During MAO, P and F compete with each other to enter into anodic coatings. F amount in MAO coatings is closely related to the coating biocompatibility. MAO coatings developed in the solution composed of both IP6 and PA achieve low F content (3.49 at%) and good biocompatibility, while those fabricated in solutions containing only IP6 or PA achieve high F content (higher than 19.00 at%) and exhibit high toxicity.

In this study, 3D porous anodic coatings containing 1.92 wt% copper (Cu-1.92 wt%) are developed on Ti-6Al-4V alloys via micro-arc oxidation (MAO). The in vitro long-term antibacterial activity of the MAO-treated samples is systematically evaluated. The results show that after 14 days’ immersion in Hanks’ solution, the antibacterial rate of Cu-1.92 wt% against Staphylococcus aureus (S. aureus) remains at 100%, while that against Escherichia coli (E. coli) decreases to 92% and 12% after 8 and 14 days, respectively, suggesting that Cu-1.92 wt% still exhibits good long-term antibacterial properties even after 14 days. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis and reactive oxygen species (ROS) fluorescence imaging reveal that the antibacterial efficiency of Cu-1.92 wt% is higher than those of Cu-1.92 wt%-8D, Cu-1.92 wt%-14D, and the untreated control. The enhanced antibacterial properties of the MAO samples are attributed to ROS-mediated DNA damage prompted by the presence of Cu in the coatings. In addition, Cu-1.92 wt% favors good initial cell adhesion and high cell viability. These results reveal that the fabricated biocompatible copper-doped 3D porous coatings exhibit good in vitro long-term antibacterial properties and have potential to be applied in the orthopaedics clinic in the future.

In this study, copper (Cu) and zinc (Zn) as well as phosphorus (P) were co-doped into a Ti–6Al–4V titanium alloy via micro-arc oxidation (MAO). The entrance mechanisms of Cu and Zn into MAO coatings were investigated by an orthogonal experiment. The results show that Cu and Zn in Cu–Zn–P coatings separately exist mainly in the forms of Cu2O and Zn3(PO4)2. The Cu content in MAO coating increases with increasing EDTA-CuNa2 and KOH concentrations and decreasing phytic acid concentration but is nearly independent of EDTA-ZnNa2 concentration. The Zn content increases with increasing EDTA-ZnNa2 concentration and decreasing EDTA-CuNa2 concentration, indicating the competing effect between Cu and Zn for incorporation into Cu–Zn–P coatings. Compared with Zn ions, Cu ions do not readily enter anodic coatings due to their simultaneous involvement in coating formation on the anode and precipitation of metallic copper on the cathode. Cu–Zn–P coatings with appropriate amounts of Cu and Zn achieve excellent antibacterial ability against Escherichia coli (E.coli), Staphylococcus aureus (S.aureus), and Methicillin-resistant Staphylococcus aureus (MRSA). These antibacterial properties, in addition to excellent cytocompatibility, make Cu–Zn–P coatings as promising materials for orthopedic applications.

Electrocatalysis is the key process for many important energy conversion reaction, such as water splitting and CO2 reduction. The development of high efficiency electrocatalysts has attracted more attention in the field of electrochemistry and photovoltaic cell. Here, a simple cation exchange method is used to prepare the bimetallic sulfides ((CoxM1-x)9S8/M/N–C, M = Ni or Cu) dodecahedral nanocages (DNCs), in which (CoxM1-x)9S8 nanoparticles are coated with N-doped carbon shell. Bimetallic sulfides exhibit enhanced electrocatalytic property for triiodide reduction reaction and oxygen evolution reaction (OER) owing to favorable compositional features and well-designed architectures. The catalytic activities extremely depend on the atom ratio of Co:M and the component. Remarkably, (Co0.75Ni0.25)9S8/N–C DNCs deliver the best electrocatalytic activity for the triiodide reduction reaction using as the low-cost Pt-free counter electrode (CE) in dye-sensitized solar cells (DSSCs). Furthermore, (Co0.64Ni0.36)9S8/Ni/N–C-1 DNCs as an OER catalyst exhibit excellent electrocatalytic property in the light of the low overpotential (326 mV) at the current density of 10 mA cm −2. This notion and expedient method of construction can be broadened to synthesize other bimetallic sulfides with preferable electrocatalytic performance.

Micro-arc oxidation (MAO) coatings containing both calcium (Ca) and magnesium (Mg) elements and possessing a proper coating porosity are desirable for surface treatment of medical Ti-6Al-4V alloys. The influences of Na2CaY, Na2MgY, KOH, and final voltage on the Ca content, Mg content, and porosity of MAO coatings developed on Ti-6Al-4V alloys were investigated by an orthogonal experiment under constant voltage control mode. The results indicate that Ca and Mg separately enter into MAO coatings primarily via diffusion, and the competition between these two elements is relatively insignificant. The increasing KOH concentration can increase both Ca and Mg amounts in MAO coatings. High solution pH, which increases with increasing KOH, Na2CaY or Na2MgY concentrations, favors formation of MAO coatings. At the same processing condition, the Ca amount in MAO coatings is higher than the Mg amount, which may be mainly attributed to the smaller solubility product constant of Ca3(PO4)2 than that of Mg3(PO4)2. Final voltage is beneficial to coating formation and has a small impact on Ca or Mg contents but is the most important factor governing coating porosity. With the increasing final voltage, the coating porosity firstly increases from 300 to 350 V, but exhibits a decreasing trend after 350 V.

The applicability of a novel macrocyclic multi-carbonyl compound, pillar[4]quinone (P4Q), as the cathode active material for lithium-ion batteries (LIBs) was assessed theoretically. The molecular geometry, electronic structure, Li-binding thermodynamic properties, and the redox potential of P4Q were obtained using density functional theory (DFT) at the M06-2X/6-31G(d,p) level of theory. The results of the calculations indicated that P4Q interacts with Li atoms via three binding modes: Li–O ionic bonding, O–Li···O bridge bonding, and Li···phenyl noncovalent interactions. Calculations also indicated that, during the LIB discharging process, P4Q could yield a specific capacity of 446 mAh g−1 through the utilization of its many carbonyl groups. Compared with pillar[5]quinone and pillar[6]quinone, the redox potential of P4Q is enhanced by its high structural stability as well as the effect of the solvent. These results should provide the theoretical foundations for the design, synthesis, and application of novel macrocyclic carbonyl compounds as electrode materials in LIBs in the future.