Lingxing Zeng

MoO2-Ordered Mesoporous Carbon Nanocomposite as an Anode Material for Lithium-Ion Batteries

In the present work, the nanocomposite of MoO2-ordered mesoporous carbon (MoO2-OMC) was synthesized for the first time using a carbon thermal reduction route and the mesoporous carbon as the nanoreactor. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. Furthermore, this nanocomposite was used as an anode material for Li-ion intercalation and exhibited large reversible capacity, high rate performance, and good cycling stability. For instance, a high reversible capacity of 689 mAh g(-1) can remain after 50 cycles at a current density of 50 mA g(-1). It is worth mentioning that the MoO2-OMC nanocomposite electrode can attain a high reversible capacity of 401 mAh g(-1) at a current density as high as 2 A g(-1). These results might be due to the intrinsic characteristics of nanocomposite, which offered a better accommodation of the strain and volume changes and a shorter path for Li-ion and electron transport, leading to the improved capacity and enhanced rate capability.

Ordered mesoporous TiO2–C nanocomposite as an anode material for long-term performance lithium-ion batteries

A nanocomposite of ordered mesoporous pure anatase TiO2–C was successfully synthesized for the first time by using ordered mesoporous carbon as a nano-reactor and exhibited a short-range ordered mesoporous structure. It was found that carbon was coated on the surface of TiO2 nanoparticles to form a thin layer. Using this material as an anode in rechargeable lithium-ion batteries, it displayed a large reversible capacity, high rate performance and excellent long-term cycling stability. For instance, a large reversible capacity of 166 mA h g−1 and an average Coulombic efficiency of 99.7% could be maintained even after 900 cycles at a current rate of 1 C. This can be attributed to the structure of the ordered mesoporous TiO2–C nanocomposite. Such a nanostructure provides both electron and lithium-ion pathways which are essential for rechargeable lithium-ion batteries with a large capacity and excellent long-term performance.

Magnetic mesoporous organic-inorganic NiCo2O4 hybrid nanomaterials for electrochemical immunosensors.

This study demonstrates a facile and feasible strategy toward the development of advanced electrochemical immunosensors based on chemically functionalized magnetic mesoporous organic-inorganic hybrid nanomaterials, and the preparation, characterization, and measurement of relevant properties of the immunosensor for detection of carcinoembryonic antigen (CEA, as a model analyte) in clinical immunoassays. The as-prepared nanomaterials composed of a magnetic mesoporous NiCo(2)O(4) nanosheet, an interlayer of Nafion/thionine organic molecules and a nanogold layer show good adsorption properties for the attachment of horseradish peroxidase-labeled secondary anti-CEA antibody (HRP-anti-CEA). With a sandwich-type immunoassay format, the functional bionanomaterials present good analytical properties to facilitate and modulate the way it was integrated onto the electrochemical immunosensors, and allows the detection of CEA at a concentration as low as 0.5 pg/mL. Significantly, the immunosensor could be easily regenerated by only using an external magnet without the need of any dissociated reagents. Importantly, the as-synthesized magnetic mesoporous NiCo(2)O(4) nanomaterials could be further extended for detection of other biomarkers or biocompounds.

In situ synthesis of GeO2/reduced graphene oxide composite on Ni foam substrate as a binder-free anode for high-capacity lithium-ion batteries

A GeO2/RGO composite was successfully fabricated via alternating deposition of graphene oxide (GO) and GeO2 on the surface of a Ni foam substrate using a facile dip-coating method cooperated with in situ hydrolysis of GeCl4. This material was directly used as a binder-free anode for LIBs and exhibited high reversible capacity (1716 mA h g−1 at 0.2 A g−1, 702 mA h g−1 at 16 A g−1), good cycling performance (1159 mA h g−1 at 1 A g−1 after 500 cycles) and excellent rate capability. In addition, a reversible capacity as high as 621 mA h g−1 can be retained when cycled to 500 cycles at a rate as high as 8 A g−1.

Synthesis of hierarchical ZnV2O4 microspheres and its electrochemical properties

Hierarchical ZnV2O4 microspheres were synthesized using an ethanol thermal reduction route for the first time, in which vanadium with a low valence can be formed. ZnV2O4 microspheres were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), transmission electron microscopy (SEM/TEM) and N2 adsorption–desorption measurements. Furthermore, this material was used as an anode for Li ion intercalation and exhibited high reversible capacity, high rate performance, and good cycling stability. For instance, a high reversible capacity of 638 mA h g−1 was maintained after 280 cycles at a current density of 100 mA g−1. These results might be attributed to the facts that hierarchical ZnV2O4 microspheres could buffer the strain and volume changes during the charge–discharge cycling process, and provide more sites for Li ion storage and a shorter path for Li ion diffusion, leading to improved capacity and high rate performance.

Sensitive electrochemical microbial biosensor for p-nitrophenylorganophosphates based on electrode modified with cell surface-displayed organophosphorus hydrolase and ordered mesopore carbons

A novel electrochemical microbial biosensor for the rapid monitoring of p-nitrophenyl-substituted organophosphates (OPs) compounds based on glass carbon electrode (GCE) modified with both ordered mesopore carbons (OMCs) and cell surface-expressed organophosphorus hydrolase (OPH) (OPH-bacteria/OMCs/GCE) was described in this paper. The genetically engineered Escherichia coli strain surface displayed mutant OPH (S5) with improved enzyme activity and favorable stability was constructed using a newly identified N-terminal of ice nucleation protein as an anchoring motif, which can be used directly without further time-consuming enzyme-extraction and purification, thereafter greatly improved the stability of the enzyme. Compared to OPH-bacteria modified GCE (OPH-bacteria/GCE), the OPH-bacteria/OMCs/GCE not only significantly enhanced the current response but also reduced the oxidation overpotential towards oxidizable p-nitrophenol (p-NP), which was the hydrolysate of p-nitrophenyl-substituted OPs. Under the optimized experimental conditions, at +0.84 V (vs. SCE), the current-time curve was performed with varying OPs concentration. The current response was linear with paraoxon concentration within 0.05-25 μM. Similarly, linear range of 0.05-25 μM was found for parathion, and 0.08-30 μM for methyl parathion. The low limits of detection were evaluated to be 9.0 nM for paraoxon, 10nM for parathion and 15 nM for methyl parathion (S/N=3). Thus, a highly specific, sensitive and rapid microbial biosensor was established, which holds great promise for on-site detection of trace p-nitrophenyl-substituted OPs.

Ultrasensitive electrochemical sensor for p-nitrophenyl organophosphates based on ordered mesoporous carbons at low potential without deoxygenization

p-Nitrophenyl organophosphates (OPs) including paraoxon, parathion and methyl parathion, etc, are highly poisonous OPs, for which sensitive and rapid detection method is most needed. In this work, an ultrasensitive electrochemical sensor for the determination of p-nitrophenyl OPs was developed based on ordered mesoporous carbons (OMCs) modified glassy carbon electrode (GCE) (OMCs/GCE). The electrochemical behavior and reaction mechanism of p-nitrophenyl OPs at OMCs/GCE was elaborated by taking paraoxon as an example. Experimental conditions such as buffer pH, preconcentration potential and time were optimized. By using differential pulse voltammetry, the current response of the sensor at -0.085 V was linear with concentration within 0.01-1.00 μM and 1.00-20 μM paraoxon. Similar linear ranges of 0.015-0.5 μM and 0.5-10 μM were found for parathion, and 0.01-0.5 μM and 0.5-10 μM for methyl parathion. The low limits of detection were evaluated to be 1.9nM for paraoxon, 3.4 nM for parathion and 2.1 nM for methyl parathion (S/N=3). Common interfering species had no interference to the detection of p-nitrophenyl OPs. The sensor can be applicable to real samples measurement. Therefore, a simple, sensitive, reproducible and cost-effective electrochemical sensor was proposed for the fast direct determination of trace p-nitrophenyl OPs at low potential without deoxygenization.

Nanocomposite Li3V2(PO4)3/carbon as a cathode material with high rate performance and long-term cycling stability in lithium-ion batteries

In the present work, nanocomposite Li3V2(PO4)3/carbon is successfully synthesized by combining a sol–gel method and a nanocasting route, and then it is characterized by means of X-ray diffraction (XRD), thermogravimetric analysis (TG), N2 adsorption–desorption, and transmission electron microscopy (TEM). Furthermore, this nanocomposite is used as a cathode material for Li-ion intercalation and exhibits large reversible capacity, high rate performance and excellent long-term cycling stability. For instance, a large reversible capacity of 95 mA h g−1 and an average Coulombic efficiency of 99.1% can be maintained even after 3000 cycles at a high rate of 20C in the potential range of 3.0–4.3 V. Moreover, the Li3V2(PO4)3/C nanocomposite delivered a large capacity of 127 mA h g−1 at a high rate of 10C in the voltage range of 3.0–4.8 V. The super results might be attributed to the unique hierarchical architecture of the Li3V2(PO4)3/carbon nanocomposite.