Peixin Zhang

Facile preparation and synergistic antibacterial effect of three-component Cu/TiO2/CS nanoparticles

Due to the outbreaks of infectious diseases caused by different pathogenic bacteria and development of antibiotic resistance, researchers are actively searching for new antibacterial agents. Synergistic antibacterial effects provide a new way to prepare antibacterial systems to fight resistant bacteria. In this study, novel copper (Cu)/titanium dioxide (TiO2)/chitosan (CS) (CTC) three-component nanoparticles were facilely prepared via photocatalytic reduction on the basis of the synergistic antibacterial principle. The structure, antibacterial activity and antibacterial mechanism of CTC were investigated systematically. The results showed that this hybrid material exhibits excellent antibacterial ability against Escherichia coli and Staphylococcus aureus due to the synergistic antibacterial effect of the Cu, TiO2 and CS components in the nanoparticles. The minimal inhibition concentrations (MIC) of CTC against E. coli and S. aureus are only 5.22 μg mL−1 and 2.61 μg mL−1, respectively, much lower than the two-component systems. Thus, the encouraging results presented in this study demonstrate great potential applications of CTC as an alternative candidate for an antibacterial agent with high antibacterial activity.

Scalable 2D Hierarchical Porous Carbon Nanosheets for Flexible Supercapacitors with Ultrahigh Energy Density

2D carbon nanomaterials such as graphene and its derivatives, have gained tremendous research interests in energy storage because of their high capacitance and chemical stability. However, scalable synthesis of ultrathin carbon nanosheets with well-defined pore architectures remains a great challenge. Herein, the first synthesis of 2D hierarchical porous carbon nanosheets (2D-HPCs) with rich nitrogen dopants is reported, which is prepared with high scalability through a rapid polymerization of a nitrogen-containing thermoset and a subsequent one-step pyrolysis and activation into 2D porous nanosheets. 2D-HPCs, which are typically 1.5 nm thick and 1-3 µm wide, show a high surface area (2406 m2 g-1 ) and with hierarchical micro-, meso-, and macropores. This 2D and hierarchical porous structure leads to robust flexibility and good energy-storage capability, being 139 Wh kg-1 for a symmetric supercapacitor. Flexible supercapacitor devices fabricated by these 2D-HPCs also present an ultrahigh volumetric energy density of 8.4 mWh cm-3 at a power density of 24.9 mW cm-3 , which is retained at 80% even when the power density is increased by 20-fold. The devices show very high electrochemical life (96% retention after 10000 charge/discharge cycles) and excellent mechanical flexibility.

In situ growth of morphology-controllable nickel sulfides as efficient counter electrodes for dye-sensitized solar cells

Nickel sulfides (NiSs) with different morphologies (nanocubes, flower-like structure, and nanospheres) have been synthesized on fluorinated tin oxide glass (FTO) substrate using a hydrothermal method, which can be used as transparent counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The morphology of NiSs can be easily tailored by using different surfactants, and the flower-like NiS structure displays remarkable electrocatalytic activity for reducing I3−. Therefore, the flower-like NiS CE used in DSSCs generates higher photoelectric conversion efficiency (7.10xa0%) which is comparable with Pt (7.05xa0%) under the same conditions. This work paves the way for the substitution of noble metal Pt by the flower-like NiS for CE in DSSCs in the future.

Synthesis of Si-Sb-ZnO Composites as High-Performance Anodes for Lithium-ion Batteries

The Si-Sb-ZnO composites were prepared by a chemical reduction-mechanical alloying method and were employed as anode materials for lithium-ion batteries. The electrochemical performance of the Si-Sb alloy was significantly improved by the addition of ZnO nanoparticles. Especially, the initial specific charge and discharge capacities for Si-Sb-(ZnO)0.3 composite were 845.1 and 1301.5 mAh/g, respectively, while the initial coulombic efficiency was 64.9xa0%. The capacity remained at 690xa0mAh/g after 200xa0cycles, and the capacity retention ratio was 81.6xa0%, which demonstrated excellent cycling stability and rate capability of the composite materials.

In situ surface decoration of Fe 3 C/Fe 3 O 4 /C nanosheets: Towards bi-functional activated carbons with supercapacitance and efficient dye adsorption

This work reports a bi-functional activated porous carbon (PC) prepared from a biomass tofu, with excellent capacities for charge storage and adsorption of organic dyes, which is enabled by decorating with Fe3C/Fe3O4/C nanosheets. The in-situ growth and self-assembly of the nanosheets on the carbon surface are achieved by a one-step catalytic carbonization of tofu simultaneously with FeCl3 and ZnCl2 catalysts. Due to the high surface area and unique iron compounds-containing and sheet-like structures, the PCs exhibit an electrochemical capacitance of 315u202fFu202fg-1 at 0.5u202fAu202fg-1 as supercapacitor electrodes, and an ultrahigh adsorption capacity of 918u202fmgu202fg-1 for methylene blue (MB) and 868u202fmgu202fg-1 for Rhodamine B (RhB). This study provides a new perspective for understanding the effects of surface engineering on increasing charge storage and dye adsorption ability of biomass-derived PCs as well as for developing bi-functional PCs with novel magnetic properties.

SnSb–ZnO composite materials as high performance anodes for lithium-ion batteries

SnSb–(ZnO)x (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) composite anode materials were prepared by a chemical coprecipitation method. Their microstructures and morphologies were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM); the electrochemical performance was investigated by constant current charging–discharging, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific initial charge and discharge capacities of the synthesized SnSb–(ZnO)0.4 composite anode material were 801.6 mA h g−1 and 1064.6 mA h g−1, respectively, while the initial coulombic efficiency was 75.3%. The capacity remained at 751 mA h g−1 after 100 cycles and the capacity retention ratio was 92.5%, which demonstrated excellent electrochemical performance. The addition of ZnO significantly improved the electrochemical properties of the SnSb alloy, especially for the cycling stability and rate capability of the composite materials.

Air plasma etching towards rich active sites in Fe/N-porous carbon for the oxygen reduction reaction with superior catalytic performance

Herein, an electrocatalyst consisting of iron and nitrogen co-doped porous carbon (Fe–N/C) was prepared by catalytic carbonization of chitin with the assistance of FeCl3 and ZnCl2. The catalytic activity of Fe–N/C towards the oxygen reduction reaction (ORR) in both acidic and alkaline electrolytes was significantly enhanced by air-plasma etching for only 120 s, showing a four-electron ORR process with an onset potential and limiting current comparable to those of Pt catalysts. This performance enhancement originated from the removal of less stable sp3 and amorphous sp2 carbons which would expose more active catalytic FeN4 centers, as well as the transformation of a small fraction of iron-based nanoparticles into FeN4 species.

Three-dimensional nanoarchitecture SnSbZn–C composite nanofibers as anode materials for lithium-ion batteries

SnSbZn–carbon (SnSbZn–C)-based hybrid composite nanofibers are synthesized by electrospinning. The zero-dimensional alloy nanoparticles, SnSb and SbZn, are enclosed by one-dimensional carbon nanofibers, therefore they exhibit improved electrochemical performance as anode materials for lithium-ion batteries. For the 200th cycle, the discharge capacity remains at 663 mA h g−1 and the capacity retention is 84%, the high cycling stability can be attributed to the unique one-dimensional nanofiber structure which can accommodate the volume expansion generated during cycling, and prevent the particles from aggregating.

Facile synthesis of N-doped carbon-coated Si/Cu alloy with enhanced cyclic performance for lithium ion batteries

Nanoparticles consisting of silicon/copper/nitrogen-doped-carbon (Si/Cu/N–C) with a Si/Cu alloy core and a N–C shell have been synthesized by a two-step process, including the preparation of a Si/Cu alloy via mechanical ball milling and the preparation of Si/Cu/polydopamine (PDA) through in situ polymerization of dopamine followed by carbonization at 850 °C. Their microstructures and their electrochemical performance as an anode in lithium-ion batteries (LIB) were investigated. The composite nanoparticles show a coulomb efficiency of 74% in the first cycle and a discharge capacity of 851 mA h g−1 in the second cycle. They still retain 89% of their second-cycle capacity after 100 cycles at a current density of 0.08 mA cm−2. These results are superior to those for a Si/Cu alloy without the carbon coating, which is thought to be due to the carbon layer being able to mitigate the volume change of silicon and the nitrogen-doping can further enhance the wettability and electrical conductivity of the electrode material.