Yan Zeng

Mesoporous CoO Nanocubes @ Continuous 3D Porous Carbon Skeleton of Rose-Based Electrode for High-Performance Supercapacitor

Supercapacitors have attracted lots of attentions for energy storage because of their outstanding electrochemical properties, and various kinds of carbon materials have been used to improve the performance. In this work, we innovatively elevate a natural rose-based continuous 3D porous carbon skeleton. The as-prepared carbon skeleton is graphited to some extent and possesses hierarchical interconnected 3D porous structures, providing a high electrical conductive and electrolyte easy-infiltrated substrate for the fabrication of ideal monolithic composite electrodes. Then, we utilized it as scaffold to prepare mesoporous CoO nanocubes @ continuous 3D porous carbon skeleton of rose composite-based electrode for supercapacitor via hydrothermal approach. The obtained material exhibits a noticeable pseudocapacitive performance with a brilliant capacitance of 1672 F/g at 1 A/g and as high as 521 F/g at 40 A/g. It also should be noted that ∼82% of the capacitance was maintained after 3000 cycles at 5 A/g, and only 40% capacitance loss after 1500 cycles at a relatively high current density of 10 A/g.

Composite of Macroporous Carbon with Honeycomb-Like Structure from Mollusc Shell and NiCo2O4 Nanowires for High-Performance Supercapacitor

Novel biological carbon materials with highly ordered microstructure and large pore volume have caused great interest due to their multifunctional properties. Herein, we report the preparation of an interconnected porous carbon material by carbonizing the organic matrix of mollusc shell. The obtained three-dimensional carbon skeleton consists of hexangular and tightly arranged channels, which endow it with efficient electrolyte penetration and fast electron transfer, enable the mollusc shell based macroporous carbon material (MSBPC) to be an excellent conductive scaffold for supercapacitor electrodes. By growing NiCo2O4 nanowires on the obtained MSBPC, NiCo2O4/MSBPC composites were synthesized. When used on supercapacitor electrode, it exhibited anomalously high specific capacitance (∼1696 F/g), excellent rate performance (with the capacity retention of 58.6% at 15 A/g) and outstanding cycling stability (88% retention after 2000 cycles). Furthermore, an all-solid-state symmetric supercapacitor was also assembled based on this NiCo2O4/MSBPC electrode and showed good electrochemical performance with an energy density of 8.47 Wh/kg at 1 A/g, good stability over 10000 cycles. And we believe that more potential applications beyond energy storage can be developed based on this MSBPC.

A flexible fiber-shaped supercapacitor utilizing hierarchical NiCo2O4@polypyrrole core–shell nanowires on hemp-derived carbon

A high-performance fiber-shaped electrode composed of hierarchical NiCo2O4@polypyrrole core–shell nanowires on hemp-derived carbon (HDC) microfiber is successfully fabricated, which takes advantage of the high electrical conductivity of polypyrrole and carbon microfiber to boost the pseudocapacitive performance. The as-synthesized electrode exhibits an ultrahigh specific capacitance of 2055 F g−1, excellent rate performance and outstanding cycling stability (90% capacity retention over 5000 cycles). Based on the good mechanical flexibility and stability of the HDC, a fiber-shaped all-solid-state symmetric supercapacitor is designed which demonstrates a high energy density of 17.5 W h kg−1 at a power density of 500 W kg−1, good stability over 10 000 cycles and high physical flexibility.

Urchinlike MnO2 nanoparticles for the direct electrochemistry of hemoglobin with carbon ionic liquid electrode

In this paper an urchinlike MnO(2) nanoparticle was synthesized by hydrothermal method and applied to the protein electrochemistry for the first time. By using a carbon ionic liquid electrode (CILE) as the basal electrode, hemoglobin (Hb) was immobilized on the surface of CILE with chitosan (CTS) and MnO(2) nanoparticle composite materials. Spectroscopic results indicated that Hb molecules retained its native structure in the composite film. A pair of well-defined redox peaks appeared on the cyclic voltammogram with the formal peak potential as -0.180 V (vs. SCE), which indicated that direct electron transfer of Hb was realized on the modified electrode. The result can be attributed to the specific characteristic of MnO(2) nanoparticle and the advantages of CILE, which facilitated the electron transfer rate. The fabricated CTS-MnO(2)-Hb/CILE showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA). Under the optimal conditions the catalytic current was in linear to TCA concentration in the range from 0.5 to 16.0 mmol L(-1) with the detection limit calculated as 0.167 mmol L(-1) (3σ). The result indicated that urchinlike MnO(2) nanoparticle had the potential application in the third generation electrochemical biosensors.

Nanoflower-like CoS-decorated 3D porous carbon skeleton derived from rose for a high performance nonenzymatic glucose sensor

Novel carbon materials derived from biological species attract a great deal of attention due to their characteristic ordered and porous microstructures. In this work, a nanoflower-like CoS-decorated 3D porous carbon skeleton from rose was firstly synthesized through a facial one-pot solvothermal synthetic process and innovatively used to fabricate a high performance nonenzymatic glucose biosensor. The nanoflower-like structure of CoS provided abundant highly electrocatalytic active sites and the carbon skeleton of rose featured plenty of interconnected channels, which could enhance mass diffusion and electron transfer. The prepared sensor exhibited good electrocatalytic performance toward glucose with a linear range from 10 μM to 960 μM, a low detection limit of 2 μM and a high sensitivity of 697 μA mM−1 cm−2 at the potential of +0.45 V. Overall, this work highlights the great promise offered by this novel nanocomposite material in terms of its application in nonenzymatic sensing.

Application of flower-like SnS2 nanoparticles for direct electrochemistry of hemoglobin and its electrocatalysis

Flower-like SnS2 nanoparticles were synthesized through a hydrothermal process . By combing with hemoglobin (Hb) and the ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM]BF4), a composite biomaterial was fabricated and further used to modify a carbon ionic liquid electrode (CILE) with Nafion as a film-forming material. FT-IR and UV-Vis spectroscopic results showed that Hb retained its native structure in the composite. With the synergistic effects of the SnS2 nanoflower and IL, a couple of well-defined redox peaks of Hb appeared in the cyclic voltammogram of Nafion/Hb–SnS2–IL/CILE, which indicated that direct electron transfer between Hb and the underlying electrode was realized. The electrochemical behavior of Hb on the modified electrode was investigated by cyclic voltammetry with the electrochemical parameters such as electron transfer coefficient (α), electron transfer number (n) and heterogeneous electron transfer rate constant (ks) calculated. The fabricated electrode showed good electrocatalytic ability for the reduction of trichloroacetic acid (TCA) with a wider linear range from 0.8 to 21.0 mM and a lower detection limit of 0.27 mM (S/N = 3), indicating its potential application for the construction of a novel third-generation electrochemical biosensor.

Osteogenic activity and angiogenesis of a SrTiO3 nano-gridding structure on titanium surface

Osteogenesis and angiogenesis have been considered to be the most direct and necessary requirements for Ti-based implants used in bone regeneration. In this study, an alveolate double-layered SrTiO3 nano-gridding (NG-Sr) was obtained using two steps of anodization followed by a hydrothermal process. Different Sr gradient contents (NG-Sr0.02, NG-Sr0.04, NG-Sr0.08, NG-Sr0.12 and NG-Sr0.16) were generated by altering the precursor solution concentrations. The in vitro studies indicated that NG-Sr samples with nanoscale topography and long-lasting Sr release could enhance the biofunction of both osteoblast-like cells (MC3T3-E1 cells) and human umbilical vein endothelial cells (HUVECs) to varying degrees. The NG-Sr0.08 was the optimal substrate for MC3T3-E1 cell growth, while the NG-Sr0.04 was the best choice for HUVEC growth. In vivo X-ray analysis and histological observations demonstrated that the NG-Sr0.08 samples had notable osteogenesis and angiogenesis, as significant new bone formation and fresh blood vessels were observed. Hence, the nanoscale topography with sufficient Sr supplementation offers a new independent regulator of two types of cell growth, which should be considered in biomaterial design for regenerative medicine.

Rose petal and P123 dual-templated macro-mesoporous TiO 2 for a hydrogen peroxide biosensor

In this work, highly ordered macro-mesoporous TiO2 has been successfully synthesized using fresh rose petals and P123 (EO20PO70EO20) as dual templates through a simple soaking and calcining process. Characterization of the as-prepared TiO2 indicated that the mesoporous structure of the TiO2 was highly ordered, with a pore diameter of approximately 3nm. After electrodeposition of Pt nanoparticles onto the TiO2 as an electron transfer enhancer and the immobilization of horseradish peroxidase (HRP) onto the TiO2-modified electrode, a biosensor for detecting hydrogen peroxide (H2O2) was realized. This biosensor showed a wide linear detection range from 5μM to 8mM and a low detection limit of 1.65μM with good stability and high selectivity, suggesting that the sensor is well-suited for the detection of H2O2.

Design of alveolate Se-inserted TiO2 and its effect on osteosarcoma cells and osteoblasts

Osteosarcoma is a common clinical disease with high incidence, relapse rate and lethality. Thus it is urgently necessary to fabricate bone implants with anti-tumor functions to improve the prognosis of bone cancer. In this study, a novel double-layer TiO2 nano-grid with an outer diameter of 100 nm and an inner diameter of 35 nm is prepared by a simple two-step anodization procedure. In the outer pore of the double-layer TiO2 nano-grid, we precisely embed selenium (Se) nanoparticles using electrodeposition, and this process can be readily tailored by adjusting the time. Biological assays indicate that the prepared Se-embedded TiO2 nano-grid arrays show a dose-dependent anti-tumor effect by inducing apoptosis in MG63 cells. Compared with the Ti substrate, the Se-embedded TiO2 which has a double-layer honeycomb structure facilitates healthy cell (MC3T3-E1) growth when the electrodeposition time is less than 1 h. Thus the novel bone implants have a balanced anti-tumor effect and biocompatibility and are therefore potential candidates for the treatment of osteosarcoma.

Hollow Co3O4 nanospheres for the direct electrochemistry and electrocatalysis of hemoglobin with an ionic liquid as an enhancer

Hollow Co3O4 nanospheres were synthesized through a solvothermal route and applied to fabricate a redox protein-based sensing platform. Hemoglobin (Hb) was selected as the model protein to investigate the electrocatalytic properties of the composite film composed of hollow Co3O4 nanospheres, ionic liquid (IL) 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM]BF4) and Nafion, with a carbon ionic liquid electrode (CILE) as the substrate electrode. UV-vis absorption and FT-IR spectra results indicate that Hb remained in its native structure in the composite film. The results of cyclic voltammograms show that Hb entrapped in the composite film exhibited an excellent direct electrochemistry, and retained its biocatalytic activity toward the electro-reduction of trichloroacetic acid (TCA), with a linear range from 1.0 to 20.0 mmol L−1. The results could be attributed to the synergistic effect of hollow Co3O4 nanospheres and IL in the composite film, which provided a specific microenvironment to keep the native structure of Hb and promote the electron transfer rate of Hb. The fabricated biosensor displays high sensitivity, good reproducibility and long-term stability.