Boron-doped graphene-supported manganese oxide nanotubes as efficient non-metal catalyst for oxygen reduction reaction

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordAn efficient, low cost and non-precious hybrid metal catalyst compound, consisting of boron-doped graphene nanosheets (BGNS) and manganese oxide nanotube (MnO2) is used as a catalyst for oxygen reduction reaction (ORR). The morphological, chemical composition and electrochemical properties of the as-synthesized BGNS-MnO2 composite (MnO2@BGNS) were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, linear sweep voltammetry and rotating disk electrode (RDE). The asprepared BGNS-MnO2-modified glassy carbon electrode (GCE) displayed excellent catalytic activity towards ORR in an alkaline medium compared to the pure MnO2 and pure BGNS. In addition, the hybrid electrode exhibited superior electrocatalytic stability and preferable methanol tolerance compared to commercial platinum electrocatalyst in an alkaline media. This is due to the synergistic effect between the excellent catalytic activity of the MnO2 nanotubes and the large surface area and high conductivity of BGNS. Moreover, density functional theory (DFT) calculations show a strong binding energy between BGNS and MnO2 in the form of strong electrostatic interaction and inter charge transfer. The enhanced reactivity of MnO2@BGNS is due to the strong bonding between the boron (BGNS) and oxygen (MnO2). Moreover, the electron density difference and partial density of state (PDOS) analysis suggest that the electron transfer capability of B–O bonding is stronger than the C–O bonding. Finally, we conclude that boron doping of graphene is an effective strategy for fabricating an efficient ORR catalysts

Surface plasmon resonance and photoluminescence studies of Au and Ag micro-flowers

The surface plasmon resonance (SPR) and photoluminescence characteristics of gold and silver micro-flowers were compared to those of gold and silver nanoparticles. The microflower structures were grown under electron beam deposition using an alumina template. Both types of metallic micro-flowers showed systematic arrangements; they formed islands of flowers about 20 μm across, each one comprised of spikes ranging from 1 to 5 μm in length. A red shift in the SPR and enhancement intensity was observed for both micro-flowers and nanoparticles; the incremental increase was more than 50%. These results, which showed that gold and silver microflowers agglomerate at a micron size scale, are useful for the design of easier and more cost effective methods for large area fabrication, especially for particular plasmonic applications

Enhanced Photovoltaic Performance of Polymer Hybrid Nanostructure Heterojunction Solar Cells Based on Poly(3-hexylthiophene)/ZnS/ZnO/Reduced Graphene Oxide Shell–Core Nanorod Arrays

A novel hybrid photoanode based on poly(3-hexylthiophene) (P3HT) modified ZnS/ZnO shell–core nanorod arrays was fabricated on indium tin oxide (ITO) modified reduced graphene oxide (rGO) film using a simple sequential electrodeposition process. The morphology and structure of the as-fabricated electrode were confirmed by X-ray diffraction, field emission electron microscopy, and high-resolution transmission electron microscopy. The electrochemical impedance spectroscopy and current–voltage curve measurements illustrated that the power conversion efficiency of the P3HT/ZnO nanorod arrays electrode was significantly improved by the formation of rGO film and type II band alignment in the heterostructure ZnS/ZnO shell–core nanorod arrays in the four-component P3HT/ZnS/ZnO/rGO electrode. On the basis of these results, P3HT as an excellent hole acceptor, ZnS as an electronic mediator, ZnO as an excellent electron acceptor and direct pathway, and rGO nanosheet as a superior conductive collector and transporter have been shown to have in total a significant effect on increasing photovoltaic efficiency

Significantly improved photocurrent response of ZnS-reduced graphene oxide composites

ZnS-nanoparticles (NPs) reduced graphene oxide (rGO) composites with a high degree of crystallinity and high dispersity were successfully synthesized via a facile solvothermal method in the gelatin medium, during which the formation of ZnS NPs, reduction of graphene oxide and loading of ZnS NPs into the rGO surface occur simultaneously. Gelatin, as a natural capping agent, plays a significant role in controlling the degree of dispersion and coverage of ZnS NPs. The effect of rGO on the crystalline structure and optical properties of ZnS NPs were determined via X-ray diffraction, UV-visible diffused reflectance spectroscopy and photoluminescence spectroscopy. The ZnS-rGO composites exhibit excellent potential for photocurrent generation compared with pure ZnS NPs under visible light irradiation, provided that efficient photoinduced charge separation and transportation can be achieved at the interface. The maximum photocurrent response was obtained for ZnS-rGO composite with a 3% mass fraction of rGO, which is 2 times that achieved on pure ZnS NPs. (C) 2015 Elsevier B.V. All rights reserved

Electrodeposition of flower-like platinum on electrophoretically grown nitrogen-doped graphene as a highly sensitive electrochemical non-enzymatic biosensor for hydrogen peroxide detection

An efficient non-enzymatic biosensor electrode consisting of nitrogen-doped graphene (N-graphene) and platinum nanoflower (Pt NF) with different N-graphene loadings were fabricated on indium tin oxide (ITO) glass using a simple layer-by-layer electrophoretic and electrochemical sequential deposition approach. N-graphene was synthesized by annealing graphene oxide with urea at 900 degree C. The structure and morphology of the as-fabricated non-enzymatic biosensor electrodes were determined using X-ray diffraction, field emission electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectra. The as-fabricated Pt NF-N-graphene-modified ITO electrodes with different N-graphene loadings were utilized as a non-enzymatic biosensor electrode for the detection of hydrogen peroxide (H2O2). The behaviors of the hybrid electrodes towards H2O2 reduction were assessed using chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy analysis. The Pt NF-N-graphene-modified ITO electrode with a 0.05 mg ml-1 N-graphene loading exhibited the lowest detection limit, fastest amperometric sensing, a wide linear response range, excellent stability and reproducibility for the non-enzymatic H2O2 detection, due to the synergistic effect between the electrocatalytic activity of the Pt NF and the high conductivity and large surface area of N-graphene.High Impact Research MoE Grant UM.C/625/1/HIR/MoE/SC/04 from the Ministry of Education Malaysia, UMRG Program RP012A-14SUS, RP038C-15HTM, Grand Challenge GC001C-14SBS and University Malaya Centre for Ionic Liquids (UMCiL). Global Frontier R&D Program on Center for Wave Energy Control based on Metamaterials funded by the National Research Foundation under the Ministry of Science, ICT & Future Planning, Korea (No. 2014063711).Scopu

Nitrogen-doped graphene-silver nanodendrites for the non-enzymatic detection of hydrogen peroxide

An organic-metal hybrid film based on nitrogen-doped graphene-silver nanodendrites (Ag-NG) was fabricated on an indium tin oxide (ITO) electrode using a simple electrophoretic and electrochemical sequential deposition approach. The microwave-assisted method was utilized for the synthesis of nitrogen-doped graphene. This method involves a three-step process consisting of graphite oxidation, exfoliation, and finally chemical reduction with the use of hydrazine as the reducing agent, which leads to the simultaneous reduction of graphene oxide and production of nitrogen-doped graphene. The morphology and structure of the as-fabricated electrode were determined by X-ray diffraction, field emission electron microscopy and transmission electron microscopy. The as-prepared Ag-NG-modified ITO electrode exhibited superior electrocatalytic activity toward hydrogen peroxide (H2O2) reduction, with a wide linear detection range of 100 μM to 80 mM (r = 0.9989) and a detection limit of 0.26 μM with a signal-to-noise ratio of 3. Furthermore, the fabricated non-enzymatic H2O2 electrochemical sensor exhibited excellent stability and reproducibility

Large-scale hybrid silver nanowall-reduced graphene oxide biofilm: A novel morphology by facile electrochemical deposition

Increased attention has been focused on development of large-surface-area nanoengineered materials to enhance bone implants performance. Appropriate incorporations of functionalized carbon-based biofilms on the surface of artificial bone tissues can provide improved mechanobiological features. Besides, well-adhered potential coating interfaces corresponding wide spectrum antibacterial targets. Here, a novel morphology of hybrid silver (Ag) nanowall-green reduced graphene oxide (rGO) via facile methodology modified as-sputtered Ag grains to support Ti6Al7Nb implant (Ti67IMP) alloy. Layer-by-layer inorganic-organic topography obtained by physical vapor deposition magnetron sputtering (PVDMS) and subsequent one-step electrochemical deposition (ED) protocols. Microstructure, mechanical and wettability properties were characterized and cytocompatibility of designed composite-Ti67IMP system with human MG-63 osteosarcoma confirmed