Pengchao Si

Non-enzymatic glucose sensors based on controllable nanoporous gold/copper oxide nanohybrids.

A kind of dealloyed nanoporous gold (NPG)/ultrathin CuO film nanohybrid for non-enzymatic glucose sensing has been prepared by a simple, in-situ, time-saving and controllable two-step electrodeposition. The three-dimensional and bicontinuous nanoporous structure of the nanocomposites have been characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM), and the electrochemical tests have been estimated by cyclic voltammetry and single potential step chronoamperometry (SPSC). The optimal NPG/CuO electrode exhibits great electrocatalytic activity towards glucose oxidation and also shows obvious linear response to glucose up to 12 mM with a high sensitivity of 374.0 µA cm(-2)mM(-1) and a good detection limit of 2.8 µM (S/N=3), as well as strong tolerance against chloride poisoning and interference of ascorbic acid and uric acid.

Controllable synthesis of MnO2/polyaniline nanocomposite and its electrochemical capacitive property.

Polyaniline (PANI) and MnO2/PANI composites are simply fabricated by one-step interfacial polymerization. The morphologies and components of MnO2/PANI composites are modulated by changing the pH of the solution. Formation procedure and capacitive property of the products are investigated by XRD, FTIR, TEM, and electrochemical techniques. We demonstrate that MnO2 as an intermedia material plays a key role in the formation of sample structures. The MnO2/PANI composites exhibit good cycling stability as well as a high capacitance close to 207 F g−1. Samples fabricated with the facile one-step method are also expected to be adopted in other field such as catalysis, lithium ion battery, and biosensor.

One-step fabrication of bio-functionalized nanoporous gold/poly(3,4-ethylenedioxythiophene) hybrid electrodes for amperometric glucose sensing

We report a simple, one-step synthesis of hybrid film by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) on nanoporous gold (NPG) for applications in amperometric glucose biosensors. The enzyme, glucose oxidase (GOx), is entrapped into poly(3,4-ethylenedioxythiophene) (PEDOT) matrix, simultaneously. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) studies show the NPG preserve its original bicontinuous nanoporous structure and the PEDOT film grows uniformly with a thickness of ~10 nm. The modified electrodes have been investigated by cyclic voltammetry (CV) and single potential step chronoamperometry (SPSC). The influence of PEDOT films thickness has been explored to optimize sensor behaviors. Mediated by p-benzoquinone (BQ), the calibration curves have been obtained by applying relatively low constant potential of 200 mV (vs. SCE). The NPG/PEDOT/GOx (2CVs) biosensor exhibits high sensitivity of 7.3 μA mM(-1) cm(-2) and a wide linear range of 0.1-15 mM, making it suitable for reliable analytic applications.

Synthesis of ZnO nanowhiskers by a simple method

Abstract By means of a novel and simple method, zinc oxide (ZnO) nanowhiskers, which the diameters are about 15–30 nm and the lengths are up to 100 nm, are synthesized in the presence of a nonionic surfactant (Polyethylene glycol 400). The products are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM). These nanowhiskers have fine crystal structure. The surfactant is used to control the sizes of ZnO particles in precursor.

An overview of dealloyed nanoporous gold in bioelectrochemistry.

Nanoporous gold (NPG) obtained via dealloying of Au alloys has potential applications in a range of fields, and in particular in bioelectrochemistry. NPG possesses a three dimensional bicontinuous network of interconnected pores with typical pore diameters of ca. 30-40 nm, features that are useful for the immobilisation of enzymes. This review describes the common routes of fabrication and characterization of NPG, the use of NPG as a support for oxidoreductases for applications in biosensors and biofuel cells together with recent progress in the use of NPG electrodes for applications in bioelectrochemistry.

Graphene encapsulated Fe3O4 nanorods assembled into a mesoporous hybrid composite used as a high-performance lithium-ion battery anode material

The discovery of new anode materials and engineering their fine structures are the core elements in the development of new-generation lithium ion batteries (LIBs). To this end, we herein report a novel nanostructured composite consisting of approximately 75% Fe3O4 nanorods and 25% reduced graphene oxide (rGO). Microscopy and spectroscopy analyses have identified that the Fe3O4 nanorods are wrapped (or encapsulated) by the rGO nanosheets via covalent bonding, which further self-assemble into a mesoporous hybrid composite networked by the graphene matrix. The composite has an average pore size around 20 nm and exhibits a high surface area of 152 m2 g−1, which is 76 times as high as that of conventional Fe3O4 powder. We have used the composite as an LIB anode material to fabricate coin-type prototype cells with lithium as the cathode. Systematic half-cell testing evaluations show that the electrochemical performance of the present composite material is amongst the best of the transition metal-oxide based LIB anode materials. The performances are characterized by a high reversible capacity of 1053 mA h g−1 subjected to 250 charge–discharge cycles at 500 mA g−1 and an excellent rate capability with the deliverable energy of 788–541 mA h g−1 upon the application of high current densities of 1000–5000 mA g−1. Overall, we have demonstrated that Fe3O4 nanorod–rGO hybrid composite is an interesting and promising material for the fabrication of LIB anodes.

The fragility of Al–Ni-based glass-forming melts

In the original description of fragility, Angell (1988 J. Phys. Chem. Solids 49 863) determined the degree of fragility from the curvature on an Arrhenius plot. This paper discusses a new measurement of the fragility value. The fragility of Al–Ni-based glass-forming melts, which is seldom reported in this field, can be analysed by using data from their viscosity and thermal properties. The fragility is observed to be very high, which is in very good agreement with the low glass-forming ability of Al–Ni-based alloys.

Walnut-inspired microsized porous silicon/graphene core–shell composites for high-performance lithium-ion battery anodes

Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide (P-Si/rGO) core–shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh·g−1 at a current density of 1,000 mA·g−1, 1,600 mAh·g−1 at 2,000 mA·g−1, 1,500 mAh·g−1 at 3,000 mA·g−1, 1,200 mAh·g−1 at 4,000 mA·g−1, and 950 mAh·g−1 at 5,000 mA·g−1, and maintain a value of 1,258 mAh·g−1 after 300 cycles at a current density of 1,000 mA·g−1. Their excellent rate performance and cycling stability can be attributed to the unique structural design: 1) The graphene shell dramatically improves the conductivity and stabilizes the solid–electrolyte interface layers; 2) the inner porous structure supplies sufficient space for silicon expansion; 3) the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.

High-performance red phosphorus/carbon nanofibers/graphene free-standing paper anode for sodium ion batteries

Red phosphorus (P) has been regarded as an attractive anode material in a sodium-ion battery (SIB) due to its natural abundance and higher theoretical specific capacity. We developed a novel flexible P/carbon nanofibers@reduced graphene oxide (P/CFs@RGO) electrode for sodium-ion batteries through simple vapor-redistribution and electrospinning. In this multi-layer structured P/CFs@RGO electrode, the large volume changes of the red P layer during cycling can be easily buffered and the loss of P from carbon fibers is prevented. In addition, the electrodes have better electron transport. As the result, the as-prepared P/CFs@RGO electrode delivers a high capacity retention of 725.9 mA h g−1 after 55 cycles at 50 mA g−1 and a significant capacity of 406.6 mA h g−1 even at large current densities of 1000 mA g−1 after 180 cycles.

Lithium Dendrite Suppression and Enhanced Interfacial Compatibility Enabled by an Ex Situ SEI on Li Anode for LAGP-Based All-Solid-State Batteries

The electrode-electrolyte interface stability is a critical factor influencing cycle performance of All-solid-state lithium batteries (ASSLBs). Here, we propose a LiF- and Li3N-enriched artificial solid state electrolyte interphase (SEI) protective layer on metallic lithium (Li). The SEI layer can stabilize metallic Li anode and improve the interface compatibility at the Li anode side in ASSLBs. We also developed a Li1.5Al0.5Ge1.5(PO4)3-poly(ethylene oxide) (LAGP-PEO) concrete structured composite solid electrolyte. The symmetric Li/LAGP-PEO/Li cells with SEI-protected Li anodes have been stably cycled with small polarization at a current density of 0.05 mA cm-2 at 50 °C for nearly 400 h. ASSLB-based on SEI-protected Li anode, LAGP-PEO electrolyte, and LiFePO4 (LFP) cathode exhibits excellent cyclic stability with an initial discharge capacity of 147.2 mA h g-1 and a retention of 96% after 200 cycles.