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High energy supercapacitors based on functionalized carbon nanotubes: Effect of atomic oxygen doping via various radiation sources

Herein, carbon nanotubes (CNTs) were oxygen functionalized by irradiation with diverse radiation sources including Am-241, Sr-90, Co-60, and Na-22 for the first time to be used as the electrode material in a high-energy supercapacitor. The oxygen contents of the irradiated CNTs were fine-tuned via the energy of the radiation source. The physicochemical characterization of as-obtained CNTs was conducted by X-Ray Diffraction (XRD), Raman, and Scanning Electron Microscopy, Energy Dispersive X-Ray (SEM- EDX) analysis whereas cyclic voltammetry and galvanostatic charge-discharge techniques were performed to assess the electrochemical performance of the as-assembled symmetrical supercapacitor cells. The CNT irradiated by Am-241 radiation source offered superior specific capacitance values compared to the other irradiated CNTs thanks to its higher content of oxygen functional groups. The highest specific capacitance for CNT Am-241 sample (with 7.32% oxygen) was calculated to be 489.6 F.g−1 at a current density of 0.1 A.g−1, which was almost 2.75 fold that of non-irradiated CNT sample. The capacitance retention of as-synthesized CNT Am-241 was determined as 98.50% for the 5,000th CV cycle. The outstanding energy density of 56.90 W.h.kg−1 was achieved even at a high power density value of 9992.19 W.kg−1, comparable to the commercial batteries, will pave the way for facile fabrication of high-energy electrochemical energy storage systems based on functionalized carbon nanotubes.

Electrochemical aptasensor for sensitive detection of Cardiac troponin I based on CuNWs/MoS2/rGO nanocomposite

Cardiac troponin I (cTnI) is a “gold standard biomarker” for clinical diagnose of acute myocardial infarction (AMI). Rapid, accurate, and sensitive detection methods for cTnI are highly urgent and significant in early diagnosis and progression control. In this work, we proposed an electrochemical aptasensing platform for cTnI detection based on copper nanowires/molybdenum disulfide/reduced graphene oxide (CuNWs/MoS2/rGO) ternary nanostructure. The CuNWs/MoS2/rGO composite exhibited improved electrochemical activity due to the high electrochemical conductivity and the synergistic effect among each component, and the large surface area, which also facilitates the immobilization of aptamers. As a result, the constructed electrochemical cTnI aptasensor shows good selectivity, stability, and reproducibility towards cTnI. Under optimized conditions, the aptasensor responses cTnI linearly from 5.0 × 10−13 to 1.0 × 10−10 g mL−1 with a detection limit of 1.0 × 10−13 g mL−1 (S/N = 3). The analysis of cTnI in human blood samples demonstrated its practicability with comparable results. This work offers an alternative way for facile fabrication of CuNWs/MoS2/rGO based aptasensor for clinical biomarker detection.

Lanthanides-based multifunctional luminescent films for ratiometric humidity sensing, information storage, and colored coating

Multifunctional luminescent materials have attracted great attention because of their widely potential applications, however, fabrication of luminescent films are still great challenge. Herein, a new type of luminescent films have been developed by way of facile fabrication of solution casting method on the base of the reaction of hyaluronic acid (HA) with lanthanide ions (Tb3+ and/or Eu3+). The coordination interactions between HA and lanthanides were confirmed by FT-IR and XPS analysis. Luminescent spectra and luminescent decay curves supported the energy transfer from Tb3+ to Eu3+ ions, and the emission color of Tb-Eu co-doped films can be tuned by water molecules. Thus, HA-(Tb0.3Eu0.7) film was applied as a self-referencing and ratiometric luminescent sensor for humidity detection, where the corresponding variable colors can be observed by the naked eyes. Moreover, the HA-(Tb0.3Eu0.7) film for humidity sensing exhibited good reversibility and repeatability. Further, the luminescent films were applied as information carrier by using water as inks, and the writing and erasing was reversible. In addition, the luminescent films were also applied as colored coating. Therefore, this approach may provide a facile way for fabrication of luminescent films, which are of potential applications in sensing, information transmission, and colored coating.

A balsam pear-shaped CuO SERS substrate with highly chemical enhancement for pesticide residue detection.

Simple and traditional hydrothermal fabrication of a novel balsam pear-shaped CuO with high SERS enhancementis presented. XRD (X-ray diffraction), SEM (scanning electronic microscopy), TEM (transmission electron microscope), HRTEM (high-resolution transmission electron microscope), UV-Vis, and Raman are adopted to ensure that this balsam pear-shaped CuO with dense nanoparticle protuberance is successfully prepared. The LOD of this CuO SERS substrate is 4.79μgL-1 with R6G as molecular probe. By using DFT (density functional theory) calculation and FDTD (finite difference time domainmethod) simulation, both EM (electromagnetic enhancement) and CM (chemical enhancement) mechanisms are investigated, and the results show that these two-enhancement mechanisms can coexist in this balsam pear-shaped CuO. Finally, the prepared substrate has been applied for the determination oftrace levels of paraquat in solution, and results show that its LOD for paraquat is275μgL-1 (optimum Raman band: 1646cm-1 Raman shift), which is better than the government standard in China. Adexterous and facile way for fabrication of CuO SERS-active substrates with low cost and high performance, quite promising in detection of chemically hazardous substances and pesticide residueis provided. Graphical abstract.

Structurally Tunable pH-Responsive Luminescent Assemblies from Halogen Bonded Supra-π-amphiphiles.

Supra-amphiphiles constituted of noncovalent bonds have emerged as attractive systems for fabrication of stimuli-responsive self-assembled nanostructures. A unique supramolecular strategy utilizing halogen (X)-bonding interaction has been demonstrated for constructing emissive supra-π-amphiphiles in water from a hydrophobic pyridyl functionalized naphthalene monoimide (NMI-Py) based X-bond acceptor and hydrophilic iodotetrafluorophenyl functionalized polyethylene glycol (PEG-I) or triethylene glycol (TEG-I) based X-bond donors, while their luminescent higher ordered assemblies were governed by orthogonal dipole-dipole interaction and π-stacking of the NMI-Py fluorophore as probed by SCXRD and DFT calculations. Control molecules lacking iodotetrafluorophenyl moiety at the polyethylene glycol chain end failed to create any defined morphology from the NMI-Py, suggesting X-bonding is prerequisite for the nanostructure formation. Variation in the chain length of the X-bond donors leads to different morphologies (fiber vs vesicle) for PEG-I and TEG-I. Acid triggered denaturing of the X-bonds caused pH responsive disassembly of the thermally robust nanostructures. This strategy paves the way for facile fabrication of structurally diverse smart and adaptive luminescent functional materials with tunable morphology.

A facile way for fabrication of silver nanoparticle decorated graphene composites

With the fast development of inkjet printing, the fabrication and application of conductive ink have been the frontiers of scientific research. Compared with traditional conductive inks, the rise of graphene also reveals greatly potential applications and attracts many attentions all around the world. In this work, graphene conductive inks with and without Ag nanoparticles were prepared by direct physical methods. Through TEM characterizations, it can be clearly found the resistance of graphene without additional Ag nanoparticles is larger than that of graphene decorated by Ag. Meanwhile, the annealing process also plays an important role in increasing the conductivity of graphene-Ag system. The conductivity obtained in this work follows a rule of σannealed>σwith precursor>σw/o precursor>σpure G. Our work not only offers a reference for exploring high conductive graphene composites but also opens a way for investigating the real mechanism at the interface in graphene composites system.

Field-Driven Athermal Activation of Amorphous Metal Oxide Semiconductors for Flexible Programmable Logic Circuits and Neuromorphic Electronics.

Despite extensive research, large-scale realization of metal-oxide electronics is still impeded by high-temperature fabrication, incompatible with flexible substrates. Ideally, an athermal treatment modifying the electronic structure of amorphous metal oxide semiconductors (AMOS) to generate sufficient carrier concentration would help mitigate such high-temperature requirements, enabling realization of high-performance electronics on flexible substrates. Here, a novel field-driven athermal activation of AMOS channels is demonstrated via an electrolyte-gating approach. Facilitating migration of charged oxygen species across the semiconductor-dielectric interface, this approach modulates the local electronic structure of the channel, generating sufficient carriers for charge transport and activating oxygen-compensated thin films. The thin-film transistors (TFTs) investigated here depict an enhancement of linear mobility from 51 to 105.25 cm2 V-1 s-1 (ionic-gated) and from 8.09 to 14.49 cm2 V-1 s-1 (back-gated), by creating additional oxygen vacancies. The accompanying stochiometric transformations, monitored via spectroscopic measurements (X-ray photoelectron spectroscopy) corroborate the detailed electrical (TFT, current evolution) parameter analyses, providing critical insights into the underlying oxygen-vacancy generation mechanism and clearly demonstrating field-induced activation as a promising alternative to conventional high-temperature annealing strategies. Facilitating on-demand active programing of the operation modes of transistors (enhancement vs depletion), this technique paves way for facile fabrication of logic circuits and neuromorphic transistors for bioinspired computing.

Mesoporous Mn0.5Co0.5Fe2O4 Nanospheres Grown on Graphene for Enhanced Lithium Storage Properties

We report in situ growth of mesoporous Mn0.5Co0.5Fe2O4 (MCFO) nanospheres on graphene to form MCFO/graphene nanocomposites by a facile solvothermal method. In the synthesis, Mn(CH3COO)2, Co(CH3COO)2, and FeCl3 were used as the metal precursors and CH3COOK, CH3COOC2H5, and HOCH2CH2OH as the mixed solvent. The obtained MCFO nanospheres (50–200 nm) were composed of small nanoparticles (5–15 nm), and the graphene surface acted as the nucleation sites in growing MCFO nanospheres. Compared with the bare MCFO nanospheres and the MCFO nanospheres physically mixed with graphene, the MCFO/graphene nanocomposite with 2.1 wt % graphene as anode material in Li ion batteries showed a significantly enhanced electrochemical performance with high lithium storage capacity and excellent cycling stability. This is because the introduced graphene can prevent the aggregation of nanospheres and provides a pathway for excellent Li+ ion diffusion and electronic conduction. This work opens a way for facile fabrication of metal oxi...