In this work, we report a facile synthesis of mesoporous Co3O4 nanowires by solid-state thermal conversion of CoC2O4·2H2O precursors for supercapacitors. The formation mechanism of the ultra-long CoC2O4·2H2O nanowires is discussed based on a series of time-dependent experiments. Electrochemical measurements reveal that the mesoporous Co3O4 nanowires electrode exhibits a specific capacitance up to 250 F g−1 with a better capacity retention of 90.2% after 1000 continuous charge–discharge cycles at a constant current density of 5 A g−1. The good supercapacitor performance could be attributed to the unique mesoporous structure of the Co3O4 nanowires which provide fast ion and electron transfer.

The evolution of α-MnO2 from hollow cubes to hollow spheres was achieved by using MnCO3 as the template. The as-obtained α-MnO2 crystals were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The as-synthesized α-MnO2 hollow cubes (with the side length of about 2 µm) and hollow spheres (with the diameter of about 2 µm) were uniform particles. The as-prepared α-MnO2 hollow spheres have a large specific surface area (417 m2 g−1). A process has been proposed for the evolution of MnCO3 templates from cubes to spheres. Then, the evolution of α-MnO2 was achieved by two-step mechanism with the treatment of previously obtained MnCO3 templates. Cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS) measurements were used to characterize the electrochemical performances of the as-synthesized α-MnO2. The initial specific capacitance at a current density of 1 A g−1 of the as-prepared α-MnO2 hollow spheres is 203 F g−1, which is higher than that of α-MnO2 hollow cubes (152 F g−1). In addition, the α-MnO2 hollow cubes retain 93% and the α-MnO2 hollow spheres retain 80% of the initial specific capacitance after 2000 charge/discharge cycles at 2 A g−1. The α-MnO2 hollow spheres-based supercapacitors exhibit 38.7 W h kg−1 at a power density of 1000 W kg−1 and maintain 7.8 W h kg−1 at a high power density of 10028 W kg−1.

A simple controlled synthesis of Cu2O nanocrystals from octahedra to their different truncated forms was successfully achieved by using an ultrasonic method. The crystals were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), UV-vis spectroscopy (UV-vis) and transmission electron microscopy (TEM) as well as high-resolution transmission electron microscopy (HRTEM). The growth processes of cuprous oxide nanocrystals were analyzed and possible growth mechanisms were discussed. The optical properties of the obtained crystals were investigated.

A broad size range of cuprous oxide (Cu2O) nanocubes from 36 nm to 450 nm are obtained by an in situ seed-mediated approach that simply requires two additions of deionized water. The as-prepared Cu2O nanocubes are found to have strong antibacterial activity towards both Gram-negative and Gram-positive bacteria.

An integrated printed circuit board (PCB) based array sensing chip was developed to simultaneously detect lactate and glucose in mouse serum. The novelty of the chip relies on a concept demonstration of inexpensive high-throughput electronic biochip, a chip design for high signal to noise ratio and high sensitivity by construction of positively charged chitosan/redox polymer Polyvinylimidazole-Os (PVI-Os)/carbon nanotube (CNT) composite sensing platform, in which the positively charged chitosan/PVI-Os is mediator and electrostatically immobilizes the negatively charged enzyme, while CNTs function as an essential cross-linker to network PVI-Os and chitosan due to its negative charged nature. Additional electrodes on the chip with the same sensing layer but without enzymes were prepared to correct the interferences for high specificity. Low detection limits of 0.6 μM and 5 μM were achieved for lactate and glucose, respectively. This work could be extended to inexpensive array sensing chips with high sensitivity, good specificity and high reproducibility for various sensor applications.Graphical abstractHighlights► An integrated printed circuit board (PCB) based array sensing chip was developed. ► Simultaneous detection of lactate and glucose in serum has been demonstrated. ► The array electronic biochip has high signal to noise ratio and high sensitivity. ► Additional electrodes were designed on the chip to correct interferences.

High yield ZnS nanospheres were generated conveniently in aqueous solution with the assistance of surfactant polyvinyl pyrrolidone (PVP). The products were characterized by XRD, EDX, XPS, FESEM, TEM and HRTEM. The as-prepared ZnS nanospheres were uniform with an average diameter of 80 nm. The role of PVP in the forming of ZnS nanospheres was investigated. The results indicated that surfactant PVP plays a crucial role on the morphology and size of the products. Moreover, a tentative explanation for the growth mechanism of ZnS nanospheres was proposed. UV–vis and PL absorption spectrum were used to investigate the optical properties of ZnS nanospheres. The UV–vis spectrum indicated that the sample exhibits a dramatic blue-shift. PL spectrum reveals that ZnS nanospheres have a strong visible emission peak centered at 516 nm with excitation light of 400 nm.Graphical abstractHigh-yield ZnS nanospheres with an average diameter of 80 nm were fabricated successfully in aqueous solution at 100 °C by the assistance of surfactant PVP. It was found that PVP plays a crucial role in the formation of uniform ZnS nanospheres. A possible self-assembling growth mechanism was proposed. The UV–vis spectrum indicates that the as-prepared ZnS nanospheres exhibit a dramatic blue-shift. PL spectrum reveals that the ZnS nanospheres have a strong visible emission peak centered at 516 nm with excitation light of 400 nm.Highlights► High-yield ZnS nanospheres were generated conveniently in aqueous solution. ► The amount of surfactant PVP plays a crucial role on the morphology and size of the products. ► A tentative explanation for the growth mechanism of ZnS nanospheres was proposed. ► The UV–vis spectrum indicated that the sample exhibits a dramatic blue-shift. ► PL spectrum reveals that ZnS nanospheres have a strong visible emission peak centered at 516 nm with excitation light of 400 nm.

•A layer-by-layer film incorporating quantum dots and poly-l-lysine was fabricated.•The film shows tunable optical properties and antibacterial activity.•The film is built up in a logarithmic growth mode.Tunable absorption/emission and antibacterial activity are highly desirable for antibacterial decorative coating layers. In this study, films with both tunable optical and effective antibacterial properties were fabricated with cadmium telluride quantum dots (QDs) and poly-l-lysine (PLL) via layer-by-layer assembly. Absorption and photoluminescence spectra as well as surface morphology were examined to monitor the film growth. The films are fabricated in a logarithmic growth mode, exhibiting effective antibacterial activity against Escherichia coli and good biocompatibility to Hela cells. By changing sizes of the incorporated QDs, optical properties of the films can be easily tailored. The PLL/QDs' multilayered films may be used as colorful coating layers for applications requiring both unique optical and antibacterial properties.

Flower-like CuS nanostructures have been synthesized via a liquid precipitation route by the reaction between CuCl2·2H2O and thioacetamide (CH3CSNH2, TAA) in the ionic liquid 1-butyl-3-methyl imidazole six hexafluorophosphoric acid salts ([BMIM][PF6]) aqueous solution at room temperature. The products were characterized by X-ray powder diffraction (XRD), field emission scanning electronic microscopy (FESEM), Brunauer-Emmett-Teller (BET), Ultraviolet-Visible Spectrophotometer (UV-Vis) and Photoluminescence (PL) techniques. The as-prepared CuS nanostructures have a mean diameter of about 1 μm. A plausible mechanism was proposed to explain the formation of CuS nanostructures. The effects of experimental parameters on the formation of the products were also explored. With BET theory, it is found that the as-prepared CuS nanostructures have a specific area of 39m2/g. The Barrett-Joyner-Halenda (BJH) pore size distribution of the as-prepared CuS nanostructures presents smaller pores centers about 60 nm.The UV-Vis and PL curves indicate that the asprepared CuS nanostructures are promising candidates for the development of photoelectric devices.

Uniform copper sulfide hollow nanospheres were obtained in high yield by reacting copper nitrate with thioacetamide in water at room temperature under the assistance of sodium dodecyl sulfate (SDS). The spheres (average diameter of ca. 200 nm) displayed big cavity while their surface were constructed by randomly stacked nanoflakes. The products were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). SDS was found to play a key role in the synthesis process while a four-step mechanism was proposed to explain the formation of hollow nanospheres. The influence of SDS concentration on the size and shape of the product has also been investigated in detail.