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The design and preparation of novel carbon electrodes are the key to the development of potassium ion batteries (PIBs). The unique short-range ordered graphene sheet and defective amorphous domain composite structure of hard carbon (HC) provide favorable support for the storage and adsorption of potassium ions. In this paper, derived biomass carbons (DBCs) as a HC material were prepared by simple two-step carbonization of pre-carbonized at 500 °C and the graphitization transformation at a higher carbonization temperature employing the distilled grain biomass as a carbon source. The effect of carbonization temperature at the second step on the surface structure and electrochemical performance of the DBCs applied in PIBs were checked. It was found that 900 °C of carbonization temperature was favored for the formation of DBCs with a proper degree of graphitization, large lattice spacing (3.55 Å), and large specific surface area (111.9 m2/g−1). Ascribed to the microstructural advantage, the DBC-900 based PIBs displayed astonishing potassium storage capacity (160.5 mAh/g at 50 mA/g) and extremely low-capacity attenuation (0.041% per cycle at 50 mA/g after 800 cycles). This work not only provides a kind of HC materials with low-cost and easy preparation for PIBs, but also offers a way for the application of distilled grains.

Inorganic nanomaterials with enzyme-like activity have been attracting much attention due to their low cost, favorable stability, convenient storage, and simple preparation. Herein, Co

Ag–Cu–Pt–Pd quadrometallic nanoparticles which small Pt and Pd nanoparticles were attached on the surface of AgCu Janus nanoparticles were firstly synthesized by sequential reduction of Pt and Pd precursor in the presence of Janus AgCu bimetallic nanoparticles as seeds in an aqueous solution. Even though there was a small amount of Cu2O on the surface, the synthesized nanoparticles were mainly composed of four independent metallic part, not alloy parts. By theoretical calculation and growth mechanism study, we found that different reducing rate between Ag+ and Cu2+ and sequential reduction of Pt and Pd precursors would be key roles for the formation of the quadrometallic nanoparticles.

In this report, a Couette-Taylor (CT) reactor was applied as an effective continuous process for synthesizing copper sulfide nanoparticles. The rotational speed, mean residence time (MRT), and concentration of the feed solution were important control factors on the morphology and size control of the nanoparticles. Increasing the rotational speed from 80 rpm to 90 rpm changed the morphology of the synthesized nanoparticles from nanofibers to hexagonal nanoplates. Only Cu7S4 nanofibers were obtained in the batch reactor. Through various comparative experiments, we found that MRT and the feed solution concentration affect monomer concentration in the CT reactor, thus controlling the morphology and size of the nanoparticles.

Copper sulfide (Cu7S4) nanoparticles were synthesized by adding ethanolic elemental sulfur solution to an aqueous solution containing Cu(II) precursor, branched polyethyleneimine (BPEI), and ascorbic acid. By varying the Cu(II) precursor used, we could control the morphology of the nanoparticles produced to be either quasi spherical (CuF2, Cu(NO3)2, and CuSO4) or vine like nanofibers (CuCl2 and CuBr2). By comparing experimental results and conducting calculations we found that selective adsorption of Br− and Cl− onto specific crystal facets and slowing of the reaction rate owing to formation of Cu(I)–anion–BPEI complexes explain the observed change in morphology from spherical particles to vine like nanofibers. We also found that the differences in morphology of Cu7S4 nanoparticles affects the electrochemical performance of Li batteries including the nanoparticles as electrode materials.

In this report, a continuous stirring tank reactor (CSTR) and batch reactor were used for synthesis of silver (Ag) plates. The influences of agitation speed, molar ratio of AgNO3 to NaCl, and concentration of reagent were investigated. Size analysis demonstrated that the size of Ag plates synthesized by the CSTR was larger than the size of plates synthesized by the batch reactor. The reason might be that low concentration of reagent and continuous supply of monomer in CSTR are more favorable for growth of anisotropic structures. CSTR demonstrates good advantages for mass synthesis of Ag plates of large size.

We reported on an aqueous-phase synthesis of copper-palladium (Cu-Pd) nanoplates consisting of 5 nm-sized Pd nanoparticles deposited on Cu nanoplates. In the present synthesis, ascorbic acid was used as a reducing agent to prevent galvanic replacement. By controlling the experimental conditions, we could control the weight percent of Pd in the nanoplates from 0.56% to 2.02%. The Cu-Pd nanoplates with Pd content of 2.02% exhibited high catalytic performance in the direct H2O2 generation reaction.

Hydrogel-based flexible strain sensors have drawn significant interests due to their potential applications in the fields of wearable devices, electronic skins, soft robotics. Herein, novel Li+ ions doped agar/(N-poly(hydroxyethyl)acrylamide) (pHEAA) conductive double-network hydrogels (Li+/agar/pHEAA DN hydrogels) were synthesized and assembled as strain sensors for human motion monitoring. The incorporation of Li+ not only endowed high conductivity of the hydrogels, but also increased the interaction between the agar and pHEAA networks. At proper content of Li+ (0.8 wt%), transparent Li+/agar/pHEAA DN hydrogels with excellent mechanical performances (fracture stress of 1.18 MPa and fracture strain of 860%), good self-recovery and self-repairing properties were obtained. Ascribe to the plenty of amide and hydroxyl functional groups in pHEAA networks, the as-prepared hydrogels displayed strong self-adhesiveness on various nonporous solid surfaces (e.g., aluminum, glass, titanium, and stainless steel) with high interfacial toughness of 920–1130 J/m2 due to the multiple hydrogen bonding between the hydrogels and substrates. More impressively, the DN hydrogels can be self-adhered on human skins. Furthermore, the hydrogels also showed stretching and temperature responsiveness with high sensitivity and reliability in the form of resistance variation. Taking advantage of excellent toughness, surface adhesiveness, self-repairing and stimulus responsiveness, the as-obtained hydrogels can be applied as strain sensors for monitoring human motion in large amplitude joint movement and feeble physiological signals. We envision that the proposed Li+/agar/pHEAA DN hydrogels-based strain sensors hold great potential in health care management, disease diagnosis and artificial electronic skins.

In the synthesis of nanoparticles, the reaction rate is important to determine the morphology of nanoparticles. We investigated morphology evolution of Cu nanoparticles in this two different reactors, microemulsion reactor and batch reactor. In comparison with the batch reactor system, the enhanced mass and heat transfers in the emulsion system likely led to the relatively short nucleation time and the highly homogeneous environment in the reaction mixture, resulting in suppressing one or two dimensional growth of the nanoparticles. We believe that this work can offer a good model system to quantitatively understand the crystal growth mechanism that depends strongly on the local monomer concentration, the efficiency of heat transfer, and the relative contribution of the counter ions (Br− and Cl−) as capping agents.

We report a facile aqueous-phase synthetic route to vine-like copper sulfide (CuS) nanofibers prepared by reacting elemental sulfur with Cu+-branched polyethyleneimine (BPEI) complex obtained by the reaction of Cu2+ with ascorbic acid in the presence of BPEI. By controlling the concentration of BPEI, we could easily control the morphology of CuS from nanofibers to hollow nanoparticles. We also found that concentration of BPEI and the presence of halide anion would play important roles in the formation of vine-like CuS nanofibers.

Multi-metallic nanoparticles continue to attract attention, due to their great potential in various applications. In this paper, we report a facile aqueous-phase synthesis for multi-metallic nanoparticles, including AgPt, AgPd, CuPt, and AgCuPt, by a co-reduction method within a short reaction time of 10 min. The atomic ratio of bimetallic nanoparticles was easily controlled by varying the ratio of each precursor. In addition, we found that AgCuPt trimetallic nanoparticles had a core-shell structure with an Ag core and CuPt shell.

Additional file 1: Figure S1. (a) size distribution of nanoparticles, (b) XRD patterns of synthesized Cu-Ag-Pt-Pd nanoparticles. Figure S2. UV-vis spectrum of prepared Ag-Cu bimetallic nanoparticles. Table S1. ICP data of Cu-Ag-Pt-Pd nanoparticles.

This work describes a simple and aqueous-phase route for the synthesis of Cu nanowires (Cu NWs) having a long length of 140−180 μm, a high aspect ratio of more than 350, and long-term stability. High-quality Cu NWs were synthesized by reduction of CuCl2 with ascorbic acid in the presence of branched polyethyleneimine (BPEI) in an aqueous solution at 90 °C. The synthesized uniform Cu NWs showed long-term stability without the formation of Cu oxides on the surface of the NWs after being stored at room temperature for 40 days. Interestingly, we found that Cl− in the reacting solution played a key role in the formation of long Cu NWs. We also investigated the influence of various experimental conditions including the weight ratio of BPEI/CuCl2, the pH of the reacting solution, and the reaction temperature on the length, morphology, and stability of Cu NWs.

The basic magnesium hypochlorite (BMH) nanoparticles were prepared by two micro-emulsion techniques and modified with sodium stearate. The influences of the main technical parameters such as the addition amount of sodium stearate, reaction temperature and reaction time on the Lipophilic degree (LD) of the modified BMH nanoparticles were investigated. The characteristics of the BMH nanoparticles were analysed by means of Malvern Instruments, transmission electron microscopy (TEM), water contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). The antimicrobial activity of the modified BMH nanoparticles was investigated with the antibacterial circle test. The results showed that the average size of the BMH nanoparticles was 305 nm. The BMH nanoparticles had been successfully modified by sodium stearate and the LD of.the modified BMH nanoparticles was 8.4% when the addition amount of sodium stearate was 0.15 g, the reaction temperature was 10 °C and the reaction time was 5 h. The dispersibility and hydrophobicity of the modified BMH nanoparticles were improved and the contact angle was up to 103 °, the modified BMH nanoparticles still had excellent antimicrobial activity after modification.

Ni-Mo films were prepared by electrodeposition technique with citric acid as a complexing agent. The influence of the main technical parameters such as the concentration of Na2MoO4 x 2H2O, the current density, the bath temperature and pH on the component content in the Ni-Mo films were investigated by energy dispersive spectrometer (EDS), the microstructure and surface morphology of Ni-Mo films were characterized by employing X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results showed that the excellent Ni-Mo films with 35.51 wt% Mo was obtained when the concentration of Na2MoO4 x 2H2O was 15 g/L, the current density was 8 A/dm2, the bath temperature was 30 degrees C and the pH was 5.0. The mircostructure of the Ni-Mo films were nanocrystalline and the average size of grain was about 20.12 nm by calculating using Scherrer Equation.