A ternary single-walled carbon nanotubes/RuO2/polyindole (SWCNT/RuO2/PIn) nanocomposite was fabricated by the oxidation polymerization of indole on the prefabricated SWCNT/RuO2 binary nanocomposites. The nanocomposite was measured by FTIR, XRD, SEM, TEM, EDS and XPS, together with the electrochemical technique. The electrochemical results demonstrated that the symmetric supercapacitor used SWCNT/RuO2/PIn as electrodes presented 95% retention rate after 10000 cycles, superior capacitive performance of 1203 F·g−1 at 1 A·g−1, and high energy density of 33 W·h·kg−1 at 5000 W·kg−1. The high capacitance performance of SWCNT/RuO2/PIn nanocomposite was mainly ascribed to the beneficial cooperation effect among components. This indicated that the SWCNT/RuO2/PIn nanocomposite would be a good candidate for high-performance supercapacitors.
We report a green and facile approach for the synthesis of NiFe2O4 (NF) nanoparticles with good crystallinity. The prepared materials are studied by various techniques in order to know their phase structure, crystallinity, morphology and elemental state. The BET analysis revealed a high surface area of 80.0 m2·g−1 for NF possessing a high pore volume of 0.54 cm3·g−1, also contributing to the amelioration of the electrochemical performance. The NF sample is studied for its application in supercapacitors in an aqueous 2 mol·L−1 KOH electrolyte. Electrochemical properties are studied both in the three-electrode method and in a symmetrical supercapacitor cell. Results show a high specific capacitance of 478.0 F·g−1 from the CV curve at an applied scan rate of 5 mV·s−1 and 368.0 F·g−1 from the GCD analysis at a current density of 1 A·g−1 for the NF electrode. Further, the material exhibited an 88% retention of its specific capacitance after continuous 10000 cycles at a higher applied current density of 8 A·g−1. These encouraging properties of NF nanoparticles suggest the practical applicability in high-performance supercapacitors.
Sn-based alloy materials are considered as a promising anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), whereas they suffer from severe volume change during the discharge/charge process. To address the issue, double core–shell structured Sn–Cu@SnO2@C nanocomposites have been prepared by a simple co-precipitation method combined with carbon coating approach. The double core–shell structure consists of Sn–Cu multiphase alloy nanoparticles as the inner core, intermediate SnO2 layer anchored on the surface of Sn–Cu nanoparticle and outer carbon layer. The Sn–Cu@SnO2@C electrode exhibits outstanding electrochemical performances, delivering a reversible capacity of 396 mA·h·g−1 at 100 mA·g−1 after 100 cycles for LIBs and a high initial reversible capacity of 463 mA·h·g−1 at 50 mA·g−1 and a capacity retention of 86% after 100 cycles, along with a remarkable rate capability (193 mA·h·g−1 at 5000 mA·g−1) for SIBs. This work provides a viable strategy to fabricate double core–shell structured Sn-based alloy anodes for high energy density LIBs and SIBs.
Carbon nanotubes (CNTs) as superior support materials for functional nanoparticles (NPs) have been widely demonstrated. Nevertheless, the homogeneous loading of these NPs is still frustrated due to the inert surface of CNTs. In this work, a facile gas-phase pyrolysis strategy that the mixture of ferrocene and CNTs are confined in an isolated reactor with rising temperature is developed to fabricate a carbon-coated Fe3O4 nanoparticle/carbon nanotube (Fe3O4@C/CNT) composite. It is found the ultra-small Fe3O4 NPs (<10 nm) enclosed in a thin carbon layer are uniformly anchored on the surface of CNTs. These structural benefits result in the excellent lithium-ion storage performances of the Fe3O4@C/CNT composite. It delivers a stable reversible capacity of 861 mA·h·g−1 at the current density of 100 mA·g−1 after 100 cycles. The capacity retention reaches as high as 54.5% even at 6000 mA·g−1. The kinetic analysis indicates that the featured structural modification improves the surface condition of the CNT matrix, and contributes to greatly decreased interface impendence and faster charge transfer. In addition, the post-morphology observation of the tested sample further confirms the robustness of the Fe3O4@C/CNT configuration.
ZrMOF@CdTe nanoparticles (NPs) with high fluorescence were synthesized by hydrothermal method. The morphology, particle size distribution, compositions, fluorescence properties and stability of the synthesized ZrMOF@CdTe were analyzed via the characterization by TEM, ICP-AES and fluorescence spectrophotometry, and the effects of the reaction time and pH value on the fluorescent property of ZrMOF@CdTe NPs were discussed. The results show that ZrMOFs could maintain its morphology and structure well during the process of loading CdTe quantum dots. With the increase of the loading reaction time, the red-shifted emission peaks of ZrMOF@CdTe NPs appear, and their fluorescence gradually changes from green to red color. With the increase of the pH value and temperature of the hydrothermal reaction, the fluorescence of ZrMOF@CdTe NPs was also consistent with the red-shifted change. The fluorescent property of ZrMOF@CdTe NPs could be remained for more than 3 months. Therefore, ZrMOF@CdTe NPs synthesized by the hydrothermal method have the characteristics of simple operation, adjustable fluorescent color and high stability, and the potential application in the fields of biological detection and sensing is expected.
Novel large-sized mesoporous nanofilm-constructed macroporous SiO2 (LMNCMS) with two sets of well-defined 3D continuous pass-through macropores (pore size of 0.5–1.0 μm, wall thickness of 40–50 nm) was prepared through a dual-templating approach, and used as an advanced support for TiO2 nanocrystalline photocatalyst. The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts’ features and catalytic performance. The photocatalytic activities were evaluated by degradations of methylene blue (MB) and phenol under the simulated sunlight irradiation. To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes, experiments were conducted at wide ranges of the TiO2 loading content, calcination temperature, solution pH, and photocatalyst dosage. Nano-TiO2/LMNCMS exhibited high photocatalytic activity and stability. Rapid matter transport, good accessibility of pollutants to TiO2 and high light harvesting could mainly account for the superior photocatalytic performance. The trapping experiments were performed to identify the main reactive species in the catalytic reactions.
Polylactic acid (PLA) is one of the most promising shape memory polymers with outstanding biocompatibility, while poly(ether ether ketone) (PEEK) is a special engineering plastic with excellent mechanical performance. In this work, PEEK was selected to modify PLA, and a series of PLA blended with different PEEK contents (PLA/PEEK blends) were obtained. The effects of PEEK on thermodynamic, mechanical and shape memory properties of PLA/PEEK blends were investigated. The results showed that the thermal stability of the PLA/PEEK blend was improved with the PEEK content increase. The tensile strength reached the highest value of 20.6 MPa when the PEEK content was 10%. While the best shape memory performance occurred with the PEEK content of 15%, the shape recovery time was less than 2 s, and the shape fixation/recovery ratio was more than 99%. Furthermore, the programmable mimetic flower opening process was achieved by using PLA/PEEK blends with different PEEK content ratios. The above results indicated that the blend of an appropriate proportion of PEEK had positive effects on mechanical and deformation performances of PLA.
Effective thermal management of electronic integrated devices with high powder density has become a serious issue, which requires materials with high thermal conductivity (TC). In order to solve the problem of weak bonding between graphite and Cu, a novel Cu/graphite film/Cu sandwich composite (Cu/GF/Cu composite) with ultrahigh TC was fabricated by electro-deposition. The micro-riveting structure was introduced to enhance the bonding strength between graphite film and deposited Cu layers by preparing a rectangular array of micro-holes on the graphite film before electro-deposition. TC and mechanical properties of the composites with different graphite volume fractions and current densities were investigated. The results showed that the TC enhancement generated by the micro-riveting structure for Cu/GF/Cu composites at low graphite content was more effective than that at high graphite content, and the strong texture orientation of deposited Cu resulted in high TC. Under the optimizing preparing condition, the highest in-plane TC reached 824.3 W·m−1·K−1, while the ultimate tensile strength of this composite was about four times higher than that of the graphite film.
Good dispersibility of graphene in a medium or matrix is a critical issue in practical applications. In this work, graphene was functionalized using N-(4-hydroxyl phenyl) maleimide (4-HPM) via the Diels–Alder (DA) reaction by a one-step catalyst-free approach. The optimal reaction condition was found to be 90 °C for 12 h using dimethylformamide (DMF) as the solvent. FTIR, Raman spectroscopy, XPS and EDS proved that 4-HPM moieties were successfully grafted onto the surface of graphene. UV-vis and TGA confirmed that the grafting amount of 4-HPM was 3.75%–3.97% based on the mass of graphene. Functionalized graphene showed excellent dispersion stability when dispersed in common solvents such as ethanol, DMF, water, tetrahydrofuran and p-xylene. Meanwhile, functionalized graphene also exhibited pH sensitivity in aqueous due to the phenolic hydroxyls from the 4-HPM moieties. As a result of good dispersion stability and pH sensitivity, compared with graphene, functionalized graphene had better adsorption capacity for methylene blue (MB) from aqueous solution.
In this work, waterborne epoxy resin E44 and graphene were employed as the matrix and nanofiller, respectively, to construct composite coatings with enhanced anticorrosion performance. XRD pattern and TEM observation indicated that the obtained graphene had a stacked structure of few-layer graphitic sheets with numbers of wrinkles. SEM observations revealed that no defects or microcracks existed on the surface of graphene/epoxy coatings and the internal micropores and microcracks were filled by graphene. FTIR spectra displayed that all the characteristic absorption peaks were attributed to the epoxy resin cured with polyamide. The Tafel polarization curves showed that, as the graphene addition amount increased, the corrosive potential increased and the corrosive current decreased. ESI results proved that the addition of graphene into epoxy coatings could not only increase the impedance arc in Nyquist plots, but also increase the impedance modulus at low frequency. Finally, the enhanced anticorrosion mechanism was proposed and discussed.
Graphene is a potential candidate for applications in biomedical field. It is inevitable that graphene is in contact with the ubiquitous bacterial environment. More attention has been paid to the antimicrobial activity of graphene derivatives (graphene oxide, reduced graphene oxide) than the interaction between graphene and bacteria. Herein, we explore interaction between graphene micron-sheet and bacteria from micro (gene expression) and macro (colonies) perspectives. Results demonstrate that graphene micron-sheet accelerates the biofilm forming thus promoting pathogen expansion toward both Gram-negative bacteria E. coli and Gram-positive bacteria S. aureus. The graphene micron-sheet acts as a “habitat” for increasing bacterial attachment and biofilm forming. For E. coli, graphene micron-sheet, firstly changes the integrity of periplasmic and outer membrane components, then makes membrane-associated and cell division genes increased, and finally promotes bacterial proliferation; For S. aureus, graphene micron-sheet can accelerate biofilm forming and develop bacterial expansion owing to the regulation of the quorum-sensing system and global regulatory proteins. The work can shed new light on the range of possible mode of actions, developing a better understanding of the capabilities of graphene micron-structures.
Severe skin wounds cause great problems and sufferings to patients. In this study, an injectable wound dressing based on strontium ion cross-linked starch hydrogel (SSH) was developed and evaluated. The good inject-ability of SSH made it easy to be delivered onto the wound surface. The good tissue adhesiveness of SSH ensured a firm protection of the wound. Besides, SSH supported the proliferation of NIH/3T3 fibroblasts and facilitated the migration of human umbilical vein endothelial cells (HUVECs). Importantly, SSH exhibited strong antibacterial effects on Staphylococcus aureus (S. aureus), which could prevent wound infection. These results demonstrate that SSH is a promising wound dressing material for promoting wound healing.