Understanding Interfaces in Metal-Graphitic Hybrid Nanostructures

Interfacial Interaction in MeOx/MWNTs (Me-Cu, Ni) Nanostructures as Efficient Electrode Materials for High-Performance Supercapacitors

Due to their unique physical and chemical properties, complex nanostructures based on carbon nanotubes and transition metal oxides are considered promising electrode materials for the fabrication of high-performance supercapacitors with a fast charge rate, high power density, and long cycle life. The crucial role in determining their efficiency is played by the properties of the interface in such nanostructures, among them, the type of chemical bonds between their components. The complementary theoretical and experimental methods, including dispersion-corrected density functional theory (DFT-D3) within GGA-PBE approximation, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, X-ray photoelectron, and X-ray absorption spectroscopies, were applied in the present work for the comprehensive investigation of surface morphology, structure, and electronic properties in CuOx/MWCNTs and NiOx/MWCNTs. As a result, the type of interfacial interaction and its correlation with electrochemical characteristics were determined. It was found that the presence of both Ni-O-C and Ni-C bonds can increase the contact between NiO and MWCNTs, and, through this, promote electron transfer between NiO and MWCNTs. For NiOx/MWCNTs, better electrochemical characteristics were observed than for CuOx/MWCNTs, in which the interfacial interaction is determined only by bonding through Cu-O-C bonds. The electrochemical properties of CuOx/MWCNTs and NiOx/MWCNTs were studied to demonstrate the effect of interfacial interaction on their efficiency as electrode materials for supercapacitor applications.

Cu-based catalyst designs in CO2 electroreduction: precise modulation of reaction intermediates for high-value chemical generation

The massive emission of excess greenhouse gases (mainly CO2) have an irreversible impact on the Earth's ecology. Electrocatalytic CO2 reduction (ECR), a technique that utilizes renewable energy sources to create highly reduced chemicals (e.g. C2H4, C2H5OH), has attracted significant attention in the science community. Cu-based catalysts have emerged as promising candidates for ECR, particularly in producing multi-carbon products that hold substantial value in modern industries. The formation of multi-carbon products involves a range of transient intermediates, the behaviour of which critically influences the reaction pathway and product distribution. Consequently, achieving desirable products necessitates precise regulation of these intermediates. This review explores state-of-the-art designs of Cu-based catalysts, classified into three categories based on the different prospects of the intermediates' modulation: heteroatom doping, morphological structure engineering, and local catalytic environment engineering. These catalyst designs enable efficient multi-carbon generation in ECR by effectively modulating reaction intermediates.

Molecular Thin Films Enable the Synthesis and Screening of Nanoparticle Megalibraries Containing Millions of Catalysts

Megalibraries are centimeter-scale chips containing millions of materials synthesized in parallel using scanning probe lithography. As such, they stand to accelerate how materials are discovered for applications spanning catalysis, optics, and more. However, a long-standing challenge is the availability of substrates compatible with megalibrary synthesis, which limits the structural and functional design space that can be explored. To address this challenge, thermally removable polystyrene films were developed as universal substrate coatings that decouple lithography-enabled nanoparticle synthesis from the underlying substrate chemistry, thus providing consistent lithography parameters on diverse substrates. Multi-spray inking of the scanning probe arrays with polymer solutions containing metal salts allows patterning of >56 million nanoreactors designed to vary in composition and size. These are subsequently converted to inorganic nanoparticles via reductive thermal annealing, which also removes the polystyrene to deposit the megalibrary. Megalibraries with mono-, bi-, and trimetallic materials were synthesized, and nanoparticle size was controlled between 5 and 35 nm by modulating the lithography speed. Importantly, the polystyrene coating can be used on conventional substrates like Si/SiO_x, as well as substrates typically more difficult to pattern on, such as glassy carbon, diamond, TiO_2, BN, W, or SiC. Finally, high-throughput materials discovery is performed in the context of photocatalytic degradation of organic pollutants using Au-Pd-Cu nanoparticle megalibraries on TiO₂ substrates with 2,250,000 unique composition/size combinations. The megalibrary was screened within 1 h by developing fluorescent thin-film coatings on top of the megalibrary as proxies for catalytic turnover, revealing Au_0.53Pd_0.38Cu_0.09-TiO₂ as the most active photocatalyst composition.

Graphene supported CoO nanoparticles as an advanced catalyst for aerobic oxidation of cyclohexane

Transition metals are commonly employed as catalysts for the oxidation of cyclohexane.

Addressing the Theoretical and Experimental Aspects of Low-Dimensional-Materials-Based FET Immunosensors: A Review

Electrochemical immunosensors (EI) have been widely investigated in the last several years. Among them, immunosensors based on low-dimensional materials (LDM) stand out, as they could provide a substantial gain in fabricating point-of-care devices, paving the way for fast, precise, and sensitive diagnosis of numerous severe illnesses. The high surface area available in LDMs makes it possible to immobilize a high density of bioreceptors, improving the sensitivity in biorecognition events between antibodies and antigens. If on the one hand, many works present promising results in using LDMs as a sensing material in EIs, on the other hand, very few of them discuss the fundamental interactions involved at the interfaces. Understanding the fundamental Chemistry and Physics of the interactions between the surface of LDMs and the bioreceptors, and how the operating conditions and biorecognition events affect those interactions, is vital when proposing new devices. Here, we present a review of recent works on EIs, focusing on devices that use LDMs (1D and 2D) as the sensing substrate. To do so, we highlight both experimental and theoretical aspects, bringing to light the fundamental aspects of the main interactions occurring at the interfaces and the operating mechanisms in which the detections are based.

Selectively coupled small Pd nanoparticles on sp2-hybridized domain of graphene-based aerogel with enhanced catalytic activity and stability

The precisely coupling of metal nanoparticles with support domain are crucial to enhance the catalytic activity and stability of supported metal nanoparticle catalysts (MNPs). Here we selectively anchor Pd nanoparticles to the sp² domain in graphene-based aerogel constructed with base-washed graphene oxide (BGO) by removing oxidative debris (OD). The effects of OD on the size and chemical composition of Pd nanoparticles in aerogels are initially unveiled. The removal of OD nanoparticles prompt selective coupling of Pd nanoparticles to the exposed sp²-hybridized domain on BGO nanosheets, and then prevent it from agglomeration. As a result, the Pd nanoparticle size of self-assembled Pd/BGA is 4.67 times smaller than that of traditional Pd/graphene oxide aerogel (Pd/GA). The optimal catalytic activity of Pd/BGA for the model catalytic reduction of 4-nitrophenol is 15 times higher than that of Pd/GA. Pd/BGA could maintain its superior catalytic activity and achieves 98.72% conversion in the fifth cycle. The superior catalytic performance could be ascribed to the small Pd nanoparticles and high percentage of Pd(0) in Pd/BGA, and the enhanced electronic conductivity of Pd/BGA. These integrated merits of Pd/BGA as heterogeneous catalysts are attributed to selectively anchor Pd nanoparticles on sp²-hybridized domain of graphene-based aerogel, and strongly coupled interaction of MNPs with support. The structure-regulated BGO nanosheets could serve as versatile building blocks for fabricating MNPs/graphene aerogels with superior performance for catalytic transformation of water pollutants.

Direct observation of the formation and stabilization of metallic nanoparticles on carbon supports

Direct formation of ultra-small nanoparticles on carbon supports by rapid high temperature synthesis method offers new opportunities for scalable nanomanufacturing and the synthesis of stable multi-elemental nanoparticles. However, the underlying mechanisms affecting the dispersion and stability of nanoparticles on the supports during high temperature processing remain enigmatic. In this work, we report the observation of metallic nanoparticles formation and stabilization on carbon supports through in situ Joule heating method. We find that the formation of metallic nanoparticles is associated with the simultaneous phase transition of amorphous carbon to a highly defective turbostratic graphite (T-graphite). Molecular dynamic (MD) simulations suggest that the defective T-graphite provide numerous nucleation sites for the nanoparticles to form. Furthermore, the nanoparticles partially intercalate and take root on edge planes, leading to high binding energy on support. This interaction between nanoparticles and T-graphite substrate strengthens the anchoring and provides excellent thermal stability to the nanoparticles. These findings provide mechanistic understanding of rapid high temperature synthesis of metal nanoparticles on carbon supports and the origin of their stability.

Metal nanoparticle-decorated carbon supports are vital for many applications, ranging from energy storage and catalysis to filtration and environmental remedies. Here, using real-time electron microscopy of a single carbon nanofiber during Joule heating, the authors report atomistic mechanisms responsible for nucleation and stabilization of nanoparticles on amorphous carbon supports.

A highly sensitive enzyme-less glucose sensor based on pnictogens and silver shell–gold core nanorod composites

A novel pnictogen-based composite, pnictogen–Au@AgNRs, for the development of a highly sensitive non-enzymatic glucose sensor.

Spontaneous selective deposition of iron oxide nanoparticles on graphite as model catalysts

Iron oxide nanomaterials participate in redox processes that give them ideal properties for their use as earth-abundant catalysts. Fabricating nanocatalysts for such applications requires detailed knowledge of the deposition and growth. We report the spontaneous deposition of iron oxide nanoparticles on HOPG in defect areas and on step edges from a metal precursor solution. To study the nucleation and growth of iron oxide nanoparticles, tailored defects were created on the surface of HOPG using various ion sources that serve as the target sites for iron oxide nucleation. After solution deposition and annealing, the iron oxide nanoparticles were found to nucleate and coalesce at 400 °C. AFM revealed that the particles on the sp³ carbon sites enabled the nanoparticles to aggregate into larger particles. The iron oxide nanoparticles were characterized as having an Fe³⁺ oxidation state and two different oxygen species, Fe-O and Fe-OH/Fe-OOH, as determined by XPS. STEM imaging and EDS mapping confirmed that the majority of the nanoparticles grown were converted to hematite after annealing at 400 °C. A mechanism of spontaneous and selective deposition on the HOPG surface and transformation of the iron oxide nanoparticles is proposed. These results suggest a simple method for growing nanoparticles as a model catalyst.

Controlled Electrodeposition of Gold on Graphene: Maximization of the Defect-Enhanced Raman Scattering Response

A reliable method to prepare a surface-enhanced Raman scattering (SERS) active substrate is developed herein, by electrodeposition of gold nanoparticles (Au NPs) on defect-engineered, large area chemical vapour deposition graphene (GR). A plasma treatment strategy is used in order to engineer the structural defects on the basal plane of large area single-layer graphene. This defect-engineered Au functionalized GR, offers reproducible SERS signals over the large area GR surface. The Raman data, along with X-ray photoelectron spectroscopy and analysis of the water contact angle are used to rationalize the functionalization of the graphene layer. It is found that Au NPs functionalization of the "defect-engineered" graphene substrates permits detection of concentrations as low as 10^-16 m for the probe molecule Rhodamine B, which offers an outstanding molecular sensing ability. Interestingly, a Raman signal enhancement of up to ≈10⁸ is achieved. Moreover, it is observed that GR effectively quenches the fluorescence background from the Au NPs and molecules due to the strong resonance energy transfer between Au NPs and GR. The results presented offer significant direction for the design and fabrication of ultra-sensitive SERS platforms, and also open up possibilities for novel applications of defect engineered graphene in biosensors, catalysis, and optoelectronic devices.

Probing Ca2+-induced conformational change of calmodulin with gold nanoparticle-decorated single-walled carbon nanotube field-effect transistors

Nanomaterials are ideal for electrochemical biosensors, with their nanoscale dimensions enabling the sensitive probing of biomolecular interactions. In this study, we compare field-effect transistors (FET) comprised of unsorted (un-) and semiconducting-enriched (sc-) single-walled carbon nanotubes (SWCNTs). un-SWCNTs have both metallic and semiconducting SWCNTs in the ensemble, while sc-SWCNTs have a >99.9% purity of semiconducting nanotubes. Both SWCNT FET devices were decorated with gold nanoparticles (AuNPs) and were then employed in investigating the Ca²⁺-induced conformational change of calmodulin (CaM) - a vital process in calcium signal transduction in the human body. Different biosensing behavior was observed from FET characteristics of the two types of SWCNTs, with sc-SWCNT FET devices displaying better sensing performance with a dynamic range from 10^-15 M to 10^-13 M Ca²⁺, and a lower limit of detection at 10^-15 M Ca²⁺.

Machine-Learning Identification of the Sensing Descriptors Relevant in Molecular Interactions with Metal Nanoparticle-Decorated Nanotube Field-Effect Transistors

Carbon nanotube-based field-effect transistors (NTFETs) are ideal sensor devices as they provide rich information regarding carbon nanotube interactions with target analytes and have potential for miniaturization in diverse applications in medical, safety, environmental, and energy sectors. Herein, we investigate chemical detection with cross-sensitive NTFETs sensor arrays comprised of metal nanoparticle-decorated single-walled carbon nanotubes (SWCNTs). By combining analysis of NTFET device characteristics with supervised machine-learning algorithms, we have successfully discriminated among five selected purine compounds, adenine, guanine, xanthine, uric acid, and caffeine. Interactions of purine compounds with metal nanoparticle-decorated SWCNTs were corroborated by density functional theory calculations. Furthermore, by testing a variety of prepared as well as commercial solutions with and without caffeine, our approach accurately discerns the presence of caffeine in 95% of the samples with 48 features using a linear discriminant analysis and in 93.4% of the samples with only 11 features when using a support vector machine analysis. We also performed recursive feature elimination and identified three NTFET parameters, transconductance, threshold voltage, and minimum conductance, as the most crucial features to analyte prediction accuracy.

Graphene hybridization for energy storage applications

Graphene hybridization principles and strategies for various energy storage applications are reviewed from the view point of material structure design, bulk electrode construction, and material/electrode collaborative engineering.

Nanoelectronic Discrimination of Nonmalignant and Malignant Cells Using Nanotube Field-Effect Transistors

Detection of malignant cells in tissue is a difficult hurdle in medical diagnostics and screening. Carbon nanotubes are extremely sensitive to their local environments, and nanotube-based field-effect transistors (NTFETs) provide a plethora of information regarding the mechanism of interaction with target analytes. Herein, we use a series of functionalized metal nanoparticle-decorated NTFET devices forming an array with multiple nonselective sensor units as the electronic "tongue", sensing all five basic tastes. By extraction of selected NTFET characteristics and using linear discriminant analysis, we have successfully detected and discriminated between malignant and nonmalignant tissues and cells. We also studied the sensing mechanism and what NTFET characteristics are responsible for the variation of response between cell types, allowing for the design of future studies such as detection of malignant cells in a biopsy or the effects of malignant cells on healthy tissue.

Uncondensed Graphitic Carbon Nitride on Reduced Graphene Oxide for Oxygen Sensing via a Photoredox Mechanism

Melon, a polymeric, uncondensed graphitic carbon nitride with a two-dimensional structure, has been coupled with reduced graphene oxide (rGO) to create an oxygen chemiresistor sensor that is active under UV photoactivation. Oxygen gas is an important sensor target in a variety of areas including industrial safety, combustion process monitoring, as well as environmental and biomedical fields. Because of the intimate electrical interface formed between melon and rGO, charge transfer of photoexcited electrons occurs between the two materials when under UV (λ = 365 nm) irradiation. A photoredox mechanism wherein oxygen is reduced on the rGO surface provides the basis for sensing oxygen gas in the concentration range 300-100 000 ppm. The sensor response was found to be logarithmically proportional to oxygen gas concentration. DFT calculations of a melon-oxidized graphene composite found that slight protonation of melon leads to charge accumulation on the rGO layer and a corresponding charge depletion on the melon layer. This work provides an example of a metal-free system for solid-gas interface sensing via a photoredox mechanism.

Highly Sensitive Chemical Detection with Tunable Sensitivity and Selectivity from Ultrathin Platinum Nanowires

Ultrathin platinum nanowires obtained from wet-synthesis with no strong binding ligands exhibit very high sensitivity toward hydrogen gas (two orders of magnitude increase compared with state-of-the-art devices). Their chemical sensitivity, selectivity, and other sensing characteristics can be rationally tailored through further surface engineering. A significantly reduced cross-sensitivity toward humidity is achieved, while the hydrogen sensitivity is preserved or even enhanced.

Carbon-Based Nanomaterials for Desulfurization

The special interest in ultra-low sulfur diesel (ULSD) is informed by the need to comply with the strict government policy on low sulfur content of transportation fuels. Better knowledge of different factors that concern deep desulfurization of fuels is important to achieve ultra-low sulfur fuels and cheaper way of producing ULSD. Both the capital and operating cost of the adsorptive desulfurization process is cheaper compare to the conventional hydroprocessing. The need to produce more volume of fuel such as diesel with very low sulfur content from low grade feed stocks like heavy oil and light cycle oil (LCO) in order to meet up with the global demand for sulfur-free fuels is pertinent. Several on-going researches are pointing to the use of adsorbents for removal of sulfur compounds from the hydrocarbon refining stream. In this chapter, varieties of carbon nanomaterials suitable for adsorptive desulfurization are discussed. The approach is feasible for commercial applications with any adsorbent of an adequate lifetime of activity as well as high capacity.

Plasmon-enhanced strong visible light photocatalysis by defect engineered CVD graphene and graphene oxide physically functionalized with Au nanoparticles

The strong visible light photocatalytic activity of defect-controlled CVD graphene (GR) and graphene oxide (GO) hybrids through physical functionalization with Au atoms has been demonstrated here.

High catalytic activity of oriented 2.0.0 copper(I) oxide grown on graphene film

Metal oxide nanoparticles supported on graphene exhibit high catalytic activity for oxidation, reduction and coupling reactions. Here we show that pyrolysis at 900 °C under inert atmosphere of copper(II) nitrate embedded in chitosan films affords 1.1.1 facet-oriented copper nanoplatelets supported on few-layered graphene. Oriented (1.1.1) copper nanoplatelets on graphene undergo spontaneous oxidation to render oriented (2.0.0) copper(I) oxide nanoplatelets on few-layered graphene. These films containing oriented copper(I) oxide exhibit as catalyst turnover numbers that can be three orders of magnitude higher for the Ullmann-type coupling, dehydrogenative coupling of dimethylphenylsilane with n-butanol and C–N cross-coupling than those of analogous unoriented graphene-supported copper(I) oxide nanoplatelets.

Supported metal nanoparticles have been widely used as heterogeneous catalysts. Here, the authors report the synthesis of (1.1.1) copper on few layer graphene which oxidize to orientated (2.0.0) copper(I) oxide nanoplatelets which display high catalytic activity for a number of organic coupling reactions.

Nano-gold corking and enzymatic uncorking of carbon nanotube cups

Because of their unique stacked, cup-shaped, hollow compartments, nitrogen-doped carbon nanotube cups (NCNCs) have promising potential as nanoscale containers. Individual NCNCs are isolated from their stacked structure through acid oxidation and subsequent probe-tip sonication. The NCNCs are then effectively corked with gold nanoparticles (GNPs) by sodium citrate reduction with chloroauric acid, forming graphitic nanocapsules with significant surface-enhanced Raman signature. Mechanistically, the growth of the GNP corks starts from the nucleation and welding of gold seeds on the open rims of NCNCs enriched with nitrogen functionalities, as confirmed by density functional theory calculations. A potent oxidizing enzyme of neutrophils, myeloperoxidase (MPO), can effectively open the corked NCNCs through GNP detachment, with subsequent complete enzymatic degradation of the graphitic shells. This controlled opening and degradation was further carried out in vitro with human neutrophils. Furthermore, the GNP-corked NCNCs were demonstrated to function as novel drug delivery carriers, capable of effective (i) delivery of paclitaxel to tumor-associated myeloid-derived suppressor cells (MDSC), (ii) MPO-regulated release, and (iii) blockade of MDSC immunosuppressive potential.

Functionalization of graphene at the organic/water interface

A simple method for the deposition of noble metal (Pd, Au) nanoparticles on a free-standing chemical vapour deposited graphene monolayer is reported. Metal deposition can proceed using either spontaneous or electrochemically-controlled processes. The resultant nanoclusters are characterized using atomic force and electron microscopy techniques, and mapping mode Raman spectroscopy.

A simple method for the deposition of noble metal (Pd, Au) nanoparticles on a free-standing chemical vapour deposited graphene (CVD GR) monolayer is reported. The method consists of assembling the high purity CVD GR, by transfer from poly (methyl methacrylate) (PMMA), at the organic/water interface. Metal deposition can then proceed using either spontaneous or electrochemically-controlled processes. The resultant graphene-based metal nanoclusters are characterized using atomic force and electron microscopy techniques, and the location of the nanostructures underneath the graphene layer is determined from the position and the intensity changes of the Raman bands (D, G, 2D). This novel process for decoration of a single-layer graphene sheet with metal nanoparticles using liquid/liquid interfaces opens an alternative and useful way to prepare low dimensional carbon-based nanocomposites and electrode materials.

Carbon segregation-induced highly metallic ni nanoparticles for electrocatalytic oxidation of hydrazine in alkaline media

The important roles of Ni in electrocatalytic reactions such as hydrazine oxidation are limited largely by high oxidation states because of its intrinsically high oxophilicity. Here, we report the synthesis and properties of highly metallic Ni nanoparticles (NPs) on carbon black supports. We discovered that the heat treatment of as-prepared Ni NPs with an average particle size of 5.8 nm produced highly metallic Ni NPs covered with thin carbon shells, with negligible particle coarsening. The carbon shells were formed by the segregation of carbons in the Ni lattice to the surface of the Ni NPs, leaving highly metallic Ni NPs. X-ray photoelectron spectroscopic analyses revealed that the atomic ratio of metallic Ni increased from 19.2 to 71.7% as a result of the heat treatment. The NPs exhibited higher electrocatalytic activities toward the hydrazine oxidation reaction in alkaline solution, as compared to those of the as-prepared Ni NPs and commercial Ni powders.

Sensing Reversible Protein-Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors

We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor's response at various ionic strengths was analyzed. Furthermore, protein "fingerprints" of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS).

Bottom-up synthesis of anatase nanoparticles with graphene domains

Using alizarin and titanium isopropoxide, we have succeeded in preparing a hybrid form of nanostructured graphene-TiO2 following a bottom-up synthetic approach. This novel graphene-based composite offers a practical alternative to synthesizing photocatalytically active materials with maximized graphene-TiO2 interface. The molecular precursor alizarin was chosen because it efficiently binds to TiO2 through the hydroxyl groups and already possesses the graphene building block through its anthracene basis. XPS and Raman spectroscopy proved that the calcined material contained majority sp(2)-hybridized carbon that formed graphene-like clusters. XRD data showed the integrated structures maintained their anatase crystallography, therefore preserving the material's properties without going through phase transitions to rutile. The enhanced graphene and TiO2 interface was confirmed using DFT computational techniques. The photocatalytic activity of the graphene-TiO2 materials was demonstrated through degradation of methylene blue.

Well-coupled graphene and Pd-based bimetallic nanocrystals nanocomposites for electrocatalytic oxygen reduction reaction

In this paper, a series of well-coupled graphene (G) and MPd3 (M = Fe, Cu, Ag, Au, Cr, Mo, W) nanocrystals nanocomposites (G-MPd3 NCPs) have been synthesized via a versatile electrostatic assembly and hydrogen reduction strategy, i.e., sequential assembly of coordination anions and cations on excess cationic polymer modified graphene oxide to form composite precursors and then thermal treating under H2/Ar gases atmosphere. In those NCPs, the MPd3 components are uniform and smaller than 10 nm, which are well anchored on G with "naked" or "clean" surfaces. By adjusting reaction temperature, the interplay of MPd3 nanocrystals and G can be well-controlled. Below 700 °C, no sintering phenomena are observed, indicating the unprecedented dispersion and stability effect of G for MPd3 nanocrystals. All the obtained NCPs can be directly used to catalyze oxygen reduction reaction in alkaline media. Compared with single component, monometallic, and some reported non-Pt catalysts, greatly enhanced electrocatalytic performances are observed in those NCPs due to strong synergistic or coupling of their constituents. Among them, G-FePd3 NCPs exhibit the highest catalytic activity, but their current density needs to be improved compared with G-CrPd3, G-MoPd3, and G-WPd3 ones. This work not only provides a general strategy for fabricating well-coupled G-MPd3 NCPs but also paves the way for future designing multicomponent NCPs with multiple interfaces to apply in alkaline fuel cells.

Large-scale graphene micropattern nano-biohybrids: high-performance transducers for FET-type flexible fluidic HIV immunoassays

Large-scale FET-type graphene micropattern (GM) nano-biohybrid-based immunosensor (GMNS) is fabricated in a controlled fashion to detect human immunodeficiency virus 2 antibody. Flexible GMNS shows a highly sensitive response and excellent mechanical bendability. The flexible GMNS in fluidic systems also has a stable response. This is the first experimental demonstration of a large-scale flexible fluidic FET-type immunoassay based on GM nano-biohybrids.

Controlled growth of platinum nanowire arrays on sulfur doped graphene as high performance electrocatalyst

Graphene supported Pt nanostructures have great potential to be used as catalysts in electrochemical energy conversion and storage technologies; however the simultaneous control of Pt morphology and dispersion, along with ideally tailoring the physical properties of the catalyst support properties has proven very challenging. Using sulfur doped graphene (SG) as a support material, the heterogeneous dopant atoms could serve as nucleation sites allowing for the preparation of SG supported Pt nanowire arrays with ultra-thin diameters (2-5 nm) and dense surface coverage. Detailed investigation of the preparation technique reveals that the structure of the resulting composite could be readily controlled by fine tuning the Pt nanowire nucleation and growth reaction kinetics and the Pt-support interactions, whereby a mechanistic platinum nanowire array growth model is proposed. Electrochemical characterization demonstrates that the composite materials have 2-3 times higher catalytic activities toward the oxygen reduction and methanol oxidation reaction compared with commercial Pt/C catalyst.