Search

A simple hard template method and hydrothermal process have been employed to fabricate a self-standing hierarchical porous MnO 2 /graphene film. Thus-constructed electrode materials for binder-free supercapacitors exhibit a high specific capacitance of 266.3 F g −1 at the density of 0.2 A g −1 . Moreover, the two-electrode device demonstrates an excellent rate capability and cycling stability with capacitance retention of 85.1% after 2000 charge–discharge cycles at a current density of 1 A g −1 . The porous nanostructured design can effectively improve the specific surface areas and account for the shorter relaxation time for the electrodes, resulting in a high electrochemical performance. [ABSTRACT FROM AUTHOR]

An electrochemical immunosensor for quantitative detection of α-fetoprotein (AFP) in human serum was developed using graphene sheets (GS) and thionine (TH) as electrode materials and mesoporous silica nanoparticles (MSNs) loaded with ferroferric oxide (Fe 3 O 4 ) nanoparticles and horseradish peroxidase (HRP) as labels for signal amplification. In this study, the compound of GS and TH (GS–TH) was used as a substrate for promoting electron transfer and immobilization of primary antibody of AFP (Ab 1 ). MSNs were used as a carrier for immobilization of secondary antibody of AFP (Ab 2 ), Fe 3 O 4 , and HRP. The synergistic effect occurred between Fe 3 O 4 and HRP and greatly improved the sensitivity of the immunosensor. This method could detect AFP over a wide concentration range from 0.01 to 25 ng ml −1 with a detection limit of 4 pg ml −1 . This strategy may find wide potential application in clinical analysis or detection of other tumor markers. [ABSTRACT FROM AUTHOR]

Abstract: A hybrid material of graphene oxide (GO) sheets beaded with ZnO nanoparticles was prepared. The material extends over a few hundred square nanometers, in which the ZnO nanoparticles (average diameter (∼5nm)) are dispersed evenly on the GO sheet. Both the surface photovoltage or surface photocurrent intensity for the material are much stronger than for pure ZnO nanoparticles, meaning that the free charge carriers can effectively be transferred from ZnO nanoparticles to GO sheets, which can serve as a probe to monitor the electron transfer from excited ZnO to GO. Anchoring ZnO nanoparticles on two dimensional carbon nanostructures such as GO can pave a way towards the design of ordered nanostructure assemblies that can harvest light energy efficiently. [Copyright &y& Elsevier]

Abstract In this paper, we developed a simple and convenient method for incorporating graphene with anatase-rutile TiO 2 composite and applied it as photoanode to improve the photovoltaic performance of CdS QDSSCs. Our research indicated in a CdS QDSSC system, the photoelectric conversion efficiency (PCE) of anatase-rutile TiO 2 (TGr0) composite photoanode was 86% higher than that rutile TiO 2 NRs. We also found that the PCE increased first and then decreased with the change of graphene content after the graphene was introduced into the anatase-rutile TiO 2 photoanode. When the ratio of optimized graphene/anatase TiO 2 particles composite that spin-coated on rutile TiO 2 NRs photoanode was 5%, we attained a maximum PCE of 2.20%, which was 178% and 50% higher than that pure TiO 2 NRs (0.79%) and TGr0 (1.47%), respectively. Graphical abstract The structure of CdS sensitized graphene and anatase-rutile TiO 2 composite photoanode based on Cu 2 S CE. Image 1 Highlights • Incorporated the optimized graphene into anatase-rutile TiO 2 as photoanode. • The PCE of TGr0 photoanode was twice higher than that of pure rutile TiO 2 NRs. • The maximum PCE of 2.20% was 178% higher than that TGr0 photoanode. [ABSTRACT FROM AUTHOR]

Abstract A novel label-free electrochemiluminescent (ECL) immunosensor based upon luminol functionalized platinum nanoparticles loaded on graphene sheets (Lu-Pt@GS) as sensing platform was fabricated for highly sensitive and selective determination of prostate specific antigen (PSA). In this work, for the first time luminol was employed as both ECL luminescence reagent and reductants to in-situ reduce H 2 PtCl 6 forming Pt NPs on surface of GS. A great deal of luminol could be attached onto the surface of Pt NPs within the reduction process, which can generate strong ECL emission. Pt NPs not only could enhance ECL signals of luminol but supply active sites for the immobilization of PSA antibodies with micro friendly environment. For preventing the consecutive reaction among luminol and H 2 O 2 , single-step cycle pulse was adopted, resulting in stable and strong ECL signals. Under optimized experimental conditions, the proposed ECL immunosensor acquired a wide linear range of 1 pg/mL to 10 ng/mL with a relatively low detection limit of 0.3 pg/mL for PSA. Furthermore, due to high sensitivity, simplicity and cost-effectiveness, the designed immunosensor provides a new method for detecting other important biomarkers in clinical analysis. Highlights • ECL immunosensor was designed based upon Lu-Pt@GS for PSA detection. • Luminol was employed as both ECL luminescence reagent and reductants of Pt NPs. • Single-step cycle pulse was adopted to get stable and strong ECL signals. [ABSTRACT FROM AUTHOR]

Abstract: A novel hedgehog-like core/shell structure, consisting of a high density of vertically aligned graphene sheets and a thin graphene shell/a copper core (VGs-GS/CC), has been synthesized via a simple one-step synthesis route using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Scanning and transmission electron microscopy investigations show that the morphology of this core/shell material could be controlled by deposition time. For a short deposition time, only multilayer graphene shell tightly surrounds the copper particle, while as the deposition time is relative long, graphene sheets extend from the surface of GS/CC. The GS can protect CC particles from oxidation. The growth mechanism for the obtained GS/CC and VGs-GS/CC has been revealed. Compared to VGs, VGs-GS/CC material exhibits a better electron field emission property. This investigation opens a possibility for designing a core/shell structure of different carbon–metal hybrid materials for a wide variety of practical applications. [Copyright &y& Elsevier]

Abstract: A label-free amperometric immunosensor for fast and sensitive assay of human serum chorionic gonadotropin (hCG) is presented. hCG was immobilized on nanoporous gold (NPG) foils and using hydroquinone (HQ) redox species as indicator. The variation of amperometric response to the concentration of hCG, the target antigen, was evaluated by cyclic voltammetry in phosphate-buffered solution. Taking advantage of dual-amplification effects of the NPG foils and graphene sheets (GSs), the immunosensor exhibited a specific response to hCG in the range of 0.5–40.00ngml−1 with a detection limit of 0.034ngml−1 under optimal conditions. It was demonstrated that our proposed method possesses good accuracy, acceptable precision, and reproducibility. The NPG showed a better sensitizing effect and stability as immobilization matrices. [Copyright &y& Elsevier]