Direct observation of the nanostructural evolution of electrode materials is critical to understanding lithiation and delithiation processes during cycling of batteries. Due to its real-time monitoring and high spatial resolution, in situ transmission electron microscopy (TEM) plays an important role in understanding the reaction mechanism and dynamic processes in battery materials. This paper reviews the recent progress in using in situ TEM to study individual nanostructures in battery materials using an open-cell design, including for anode materials and cathode materials in lithium ion batteries, and Li–S batteries. Through in situ TEM, the fundamental science and reaction mechanisms, including phase transformations, electrode degradation, size effects, evolution of a solid electrolyte interphase (SEI) and nanostructures, and electrolyte decomposition of nanomaterial-based electrodes were observed during lithiation and delithiation processes. These characteristics will be very useful to the development of basic guidelines for the rational design of high-performance batteries. Finally, the challenges and perspectives of observing individual nanostructures using in situ TEM during electrochemical processes still need to be discussed and addressed.

•Electrospun zirconia-embedded carbon nanofibers are facilely fabricated.•Ultrafine zirconia particles (ϕ 5 ± 2 nm) are uniformly distributed in nanofibers.•The zirconia/carbon nanofiber electrode is applied for measuring methyl parathion.•The detection limit of the zirconia-based sensor to methyl parathion is much improved.Carbon nanofibers embedded with ultrafine zirconia nanoparticles (ZrO2-CNFs) are fabricated via a new methodology. Polyvinylpyrrolidone (PVP) and polymethylmethacrylate (PMMA) binary polymers containing zirconium n-butoxide are first dissolved in dimethylformamide, and the resulting solution is electrospun and heat-treated. The tetragonal zirconia nanoparticles formed, with a size of 5 ± 2 nm in diameter, are uniformly distributed in the carbon nanofibres. Using Nafion as an additive, ZrO2-CNFs are drop-cast onto the glassy carbon electrode (ZrO2-CNF/GCE) and the modified electrode is then applied to detect methyl parathion (MP) using differential pulse voltammetry. Two linear relationships are found at the concentration ranges of 1 × 10− 9–2 × 10− 8 g/L and 2 × 10− 8–2 × 10− 7 g/L, with a detection limit of 3.4 × 10− 10 g/L (S/N > 3). The electrospun-based ZrO2-CNF is a very promising coating material for electrochemical sensing of organophosphorus compounds.Download high-res image (107KB)Download full-size image

•Hierarchical Co3O4@NiCo2O4 hybrid composites are successfully fabricated for supercapacitors.•The Co3O4@NiCo2O4 electrode exhibit excellent supercapacitor performances.•The unique nanostructure and the synergistic effect are responsible for the improved properties.Construction of core-shell heterostructures with multifunctionalities has been regarded as promising materials to improve the supercapacitor performances for single metal oxide. In our work, hierarchical Co3O4@NiCo2O4 core-shell nanosheets are successfully fabricated on Ni foam for supercapacitors. The Co3O4@NiCo2O4 electrode demonstrates excellent supercapacitor performances with the areal capacitance of 1.33 F/cm2 at 3 mA/cm2, the specific capacitance of 1330 F/g at 3 mA/cm2 and superior cycling stability of ∼100.7% after 5000 cycles. The excellent electrochemical properties for the Co3O4@NiCo2O4 hybrid composites can be ascribed to the unique core-shell nanostructures as well as the synergistic effect of Co3O4 and NiCo2O4. The as-prepared Co3O4@NiCo2O4 hybrid composites with enhanced performances could be considered as a promising electrode material for high-performance supercapacitors.

Hierarchical core/shell structures of ZnO nanorod@CoMoO4 nanoplates grown directly on Ni foam were synthesized by a two-step hydrothermal process, in which ZnO nanorod arrays were first grown on Ni foam substrate, and then CoMoO4 nanoplates were grown in multiple directions on each ZnO nanorod. The as-grown ZnO@CoMoO4 core/shell structures (on Ni foam) directly used as integrated electrodes for electrochemical capacitors demonstrated prominent electrochemical performances, i.e., a high specific capacitance of 1.52 F cm−2 at a current density of 2 mA cm−2, which was higher than that (772 mF cm−2) of the pure CoMoO4 electrode, and a good long-term cycling stability, in which the electrodes retained 109% of the initial capacitance after 5000 cycles at a scan rate of 50 mV s−1. The superior electrochemical performances suggest that the ZnO@CoMoO4 core/shell structures could be considered as a prospective electrode material for supercapacitors.

•Electrospun ZnO nanofibers were fabricated with binary polymer matrix as template.•PMMA in the fiber matrix facilitated the formation of the ZnO nanofibers.•ZnO nanofiber modified glassy carbon electrode was constructed for Cd(II) sensing.•The sensitive detection of Cd(II) was achieved with the detection limit of 1.8 nM.ZnO nanofibers (ZnO NFs) were fabricated by electrospinning a dimethylformamide solution of zinc acetate containing polyvinylpyrrolidone and polymethylmethacrylate binary polymer matrix, followed by calcination. The obtained ZnO NFs are composed of close-packed ZnO nanoparticles of ca.20 nm in diameter. With Nafion acting as adhesive, the ZnO NF coated glassy carbon electrode (ZnO NF/GCE) has been prepared and applied as a new sensing platform for heavy metal determination with square wave stripping voltammetry. The high surface area and the strong affinity to cadmium (Cd) render the ZnO NF/GCE sensitive to Cd ion measurement. The experiment parameters were optimized by the design of orthogonal experiment. Under the optimal conditions, the current response exhibits a good linear relationship with the concentration of Cd(II) ranging from 4.8 × 10−9 to 1.3 × 10−6 mol L−1,with the detection limit of 1.8 × 10−9 mol L−1 (S/N > 3). The developed sensor has been successfully applied for the determination of Cd(II) in water sample. The simultaneous analysis of Cd(II), Pb(II), Cu(II) and Hg(II) has been demonstrated to be feasible.

•Hybridization performance of DNA/mercaptohexanol mixed self-assembled monolayers on nanoAu and rough Au is investigated.•The biggest DNA hybridization density on nanoAu increases by 85% and 51% respectively than that on rough Au and planar Au.•DNA hybridization performance is almost independent of Au roughness factor Rf.•The size fitting coefficient for DNA optimal hybridization on nanoAu is 0.71, smaller than that on rough Au or planar Au.In this article we investigated the hybridization performance of thiol-modified probe DNA/mercaptohexanol (MCH) mixed self-assembled monolayers (SAMs) on nanoAu and rough Au surfaces with target DNA in 1 M electrolytical solution. The nanoAu surfaces were prepared by electrodeposition in 2 mM HAuCl4 and 0.1 M Na2SO4 aqueous solution based on different deposition time (0.33 min, 2 min, 5 min, 10 min and 20 min), deposition potential (− 0.4 V, − 0.8 V, − 1.2 V) and deposition methods (direct electrodeposition or firstly self-assembly of 1-dodecanethiol, then electrodeposition). Scanning electron microscopy (SEM) observed that size and density of gold nanoparticles formed were related to electrodeposition conditions. The rough Au surfaces were prepared by roughly hand-polishing and the gold roughness factors (Rf) were from 1 to 3. Chronocoulometry (CC) experiments showed that DNA hybridization density (HD) arrived at the biggest for 16.3 × 10− 12 mol cm− 2 when electrodeposition was performed at − 1.2 V for 10 min and the concentration ratio of probe DNA and MCH (CDNA/CMCH) for mixed assembly was 1:1. DNA hybridization performance of probe DNA/MCH mixed SAMs on some nanoAu surfaces was much better than that on rough Au or planar Au surfaces and the biggest HD for DNA optimal hybridization increased by 85% and 51% respectively. For rough Au, DNA hybridization performance was almost independent of Rf. Based on our previous reported simple DNA hybridization model, the size fitting coefficient (dc/dt) for DNA optimal hybridization on nanoAu was calculated to be 0.71, smaller than that on rough Au (0.99) or planar Au (0.93). It meant that surface coverage of probe DNA in probe DNA/MCH mixed SAMs should be much bigger on nanoAu than that on rough Au or planar Au surface for DNA optimal hybridization. These results indicated that Au surface configuration played the important role on DNA hybridization. The intermolecular repulsion and steric hindrance for DNA hybridization might be reduced on nanoAu than those on rough Au or planar Au, which possibly led to the improvement of DNA hybridization performance. The conclusions provided the important reference for constructing electrochemical DNA sensor with the optimal performance.The hybridization performance of DNA/mercaptohexanol mixed monolayers on the optimal nanoAu surface was much better than that on rough Au or planar Au surface. Hybridization density HD for DNA optimal hybridization on nanoAu increased by 85% and 51% than that on rough Au or planar Au. The size fitting coefficient dc/dt on nanoAu was 0.71, smaller than that on rough Au (0.99) or planar Au (0.93).

MnMoO4·4H2O nanoplates (NPs) grown directly on Ni foam were synthesized by a facile hydrothermal process. As-grown MnMoO4·4H2O NPs directly supported on Ni foam as integrated electrodes for electrochemical capacitors demonstrated prominent electrochemical performances with a high specific capacitance of 1.15 F cm−2 (2300 F g−1) at a current density of 4 mA cm−2 and a good cycling ability (92% of the initial specific capacitance remained after 3000 cycles). The superior electrochemical performances could be ascribed to the porous structure of interconnected MnMoO4·4H2O NPs directly grown on current collectors, which improves electrolyte diffusion efficiency and increases electron transport. These MnMoO4·4H2O NPs on Ni foam with remarkable electrochemical properties could be considered as a prospective electrode material for the application of supercapacitors.

In this work, we have developed a novel difunctional nanoplatform for targeted chemo-photothermal therapy. It is based on hollow mesoporous silica nanospheres as a carrier for anticancer drug-loading CuS nanoparticles attached on a silica nanosphere surface as a photothermal agent, and folic acid (FA) conjugated with a silica nanosphere as a cancer cell target. The nanoplatform has demonstrated a good photothermal effect and excellent doxorubicin (DOX) loading capacity (as high as 49.3 wt%). The photothermal agent and DOX can be targeted to deliver into cancer cells via a receptor mediated endocytosis pathway. Moreover, the release of DOX from the hollow mesoporous silica nanospheres can be triggered by pH and NIR light. Both chemotherapy and photothermal therapy can be simultaneously driven by irradiation with a 980 nm laser. More importantly, the combination of chemotherapy and photothermal therapy shows a better therapy effect than the individual therapies, thus demonstrating a synergistic action.

Tin disulfide (SnS2) hexagonal flakes with diameters in the range of 50−150 nm are synthesized by using SnCl2.2H2O and sodium diethyldithiocabamate as source materials via a solvothermal decomposition route. As-prepared SnS2 hexagonal nanoflakes are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and ultraviolet–visible (UV–vis) spectroscopy. The band gap energy of the SnS2 nanoflakes is measured to be 2.17 eV, and the conduction band (CB) and valence band (VB) levels of the SnS2 nanoflakes are calculated to be − 4.34 eV and − 6.55 eV respectively, showing them to be suitable for optional and electronic applications.Highlights► We synthesize Tin disulfide (SnS2) with SnCl2.2H2O and sodium diethyldithiocabamate. ► SnS2 are hexagonal flakes materials via a solvothermal decomposition route. ► SnS2 flakes, diameters among 50–150 nm, are pure high quality nanocrystals. ► The band gap energy of the SnS2 nanoflakes is measured to be 2.17 eV. ► The CB and VB levels of the SnS2 nanoflakes are -4.34 eV and -6.55 eV respectively.

A simple hydrothermal method has been developed for fabricating hemimorphite zinc silicate, Zn4Si2O7(OH)2·H2O (ZSO). Three-dimensional ZSO hierarchal superstructures are deposited on the Si substrate. The product is characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscope. The characterization results of the sample show individual ZSO hierarchical architectures are assembled by many well-aligned and highly ordered rod bundles. The morphologies of the rod bundles within the ZSO hierarchal superstructures can be conveniently controlled, by selecting the different reactant concentrations, with excellent reproducibility. The luminescence spectra showed that the ZSO hierarchical superstructure had a stronger emission peak at 436 nm and a weaker emission peak at 418 nm.A simple hydrothermal method has been developed for fabricating hemimorphite zinc silicate, Zn4Si2O7(OH)2·H2O (ZSO). Three-dimensional ZSO hierarchal superstructures composed of many well-aligned and highly ordered rod bundles are deposited on the Si substrate. The morphologies of the rod bundles within the ZSO hierarchal superstructures can be conveniently controlled, by selecting the different reactant concentrations, with excellent reproducibility.Highlights► A hydrothermal method is developed for fabricating hemimorphite zinc silicate (ZSO). ► ZSO hierarchal superstructures are composed of many well-aligned, ordered rod bundles. ► The morphologies of the ZSO hierarchal superstructures rod bundles can be controlled. ► ZSO hierarchical superstructure had a strong emission peak and a weak one.

•Three-dimensional NixCo3−xS4@NiCo2O4 (x = 1.8) composites supported on Ni foam was designed and fabricated.•The different Ni-Co stoichiometries of NixCo3−xS4 electrode materials were studied.•The NixCo3−xS4@NiCo2O4 (x = 1.8) electrode exhibited enhanced performances of areal capacitance up to 4.44 F/cm2.Three-dimensional NixCo3−xS4@NiCo2O4 (x = 1.8) hybrid nanostructures supported on Ni foam was designed and fabricated for supercapacitor. Among different Ni-Co stoichiometries of NixCo3−xS4 electrode materials studied, NixCo3−xS4 (x = 1.8) electrode materials showed the highest capacitance of 1.908 F/cm2. Moreover, the smart combination of NixCo3−xS4 (x = 1.8) and NiCo2O4 electrode materials exhibited strong synergistic effect with significantly enhanced performances of areal capacitance up to 4.44 F/cm2.Three-dimensional NixCo3−xS4@NiCo2O4 (x = 1.8) hybrid nanostructures supported on Ni foam was designed and fabricated for supercapacitor in the present study. The smart combination of NixCo3−xS4 (x = 1.8) and NiCo2O4 electrode materials exhibited strong synergistic effect with significantly enhanced performances of areal capacitance up to 4.44 F/cm2.

In this work, we have developed a novel difunctional nanoplatform for targeted chemo-photothermal therapy. It is based on hollow mesoporous silica nanospheres as a carrier for anticancer drug-loading CuS nanoparticles attached on a silica nanosphere surface as a photothermal agent, and folic acid (FA) conjugated with a silica nanosphere as a cancer cell target. The nanoplatform has demonstrated a good photothermal effect and excellent doxorubicin (DOX) loading capacity (as high as 49.3 wt%). The photothermal agent and DOX can be targeted to deliver into cancer cells via a receptor mediated endocytosis pathway. Moreover, the release of DOX from the hollow mesoporous silica nanospheres can be triggered by pH and NIR light. Both chemotherapy and photothermal therapy can be simultaneously driven by irradiation with a 980 nm laser. More importantly, the combination of chemotherapy and photothermal therapy shows a better therapy effect than the individual therapies, thus demonstrating a synergistic action.

MnMoO4·4H2O nanoplates (NPs) grown directly on Ni foam were synthesized by a facile hydrothermal process. As-grown MnMoO4·4H2O NPs directly supported on Ni foam as integrated electrodes for electrochemical capacitors demonstrated prominent electrochemical performances with a high specific capacitance of 1.15 F cm−2 (2300 F g−1) at a current density of 4 mA cm−2 and a good cycling ability (92% of the initial specific capacitance remained after 3000 cycles). The superior electrochemical performances could be ascribed to the porous structure of interconnected MnMoO4·4H2O NPs directly grown on current collectors, which improves electrolyte diffusion efficiency and increases electron transport. These MnMoO4·4H2O NPs on Ni foam with remarkable electrochemical properties could be considered as a prospective electrode material for the application of supercapacitors.