Oxidation Control to Augment Interfacial Charge Transport in Te-P3HT Hybrid Materials for High Thermoelectric Performance.

Organic-inorganic hybrid thermoelectric (TE) materials have attracted tremendous interest for harvesting waste heat energy. Due to their mechanical flexibility, inorganic-organic hybrid TE materials are considered to be promising candidates for flexible energy harvesting devices. In this work, enhanced TE properties of Tellurium (Te) nanowires (NWs)- poly (3-hexylthiophene-2, 5-diyl) (P3HT) hybrid materials are reported by improving the charge transport at interfacial layer mediated via controlled oxidation. A power factor of ≈9.8 µW (mK2)-1 is obtained at room temperature for oxidized P3HT-TeNWs hybrid materials, which increases to ≈64.8 µW (mK2)-1 upon control of TeNWs oxidation. This value is sevenfold higher compared to P3HT-TeNWs-based hybrid materials reported in the literature. MD simulation reveals that oxidation-free TeNWs demonstrate better templating for P3HT polymer compared to oxidized TeNWs. The Kang-Snyder model is used to study the charge transport in these hybrid materials. A large σE0 value is obtained which is related to better templating of P3HT on oxygen-free TeNWs. This work provides evidence that oxidation control of TeNWs is critical for better interface-driven charge transport, which enhances the thermoelectric properties of TeNWs-P3HT hybrid materials. This work provides a new avenue to improve the thermoelectric properties of a new class of hybrid thermoelectric materials.

A rapid total bacterial count method using gold nanoparticles conjugated with an aptamer for water quality assessment.

Total bacterial count is a routine parameter in microbial safety assessment used in many fields, such as drinking water and industrial water testing. The current gold standard method for counting bacteria is the plate culture method (or heterotrophic plate count) that requires a microbiology laboratory and a long turnover time of at least 24 hours. To tackle these shortcomings, we developed a rapid total bacterial count method that relies on gold nanoparticles (AuNPs) conjugated with affinity ligands to stain bacterial cells captured on a syringe filter. Two affinity ligands were exploited, i.e. a DNA aptamer (AB2) and a lectin Griffonia simplicifolia II (GSII) that recognize bacterial cell wall commonalities, i.e. peptidoglycan and its amino sugars. Upon proper formulation with addition of a surfactant, the AB2 conjugated AuNPs (AB2-AuNPs) can selectively stain bacterial cells captured on the filter membrane with a higher sensitivity than GSII-AuNPs. Measuring the staining intensity using an in-house-built handheld detector allowed us to correlate its intensity reading with the total number of bacterial units present. This bacteria quantification method, referred to as "Filter-and-Stain", had an efficient turnover time of 20 min suggesting its potential usage for rapid on-site applications. Additionally, the detection sensitivity provided by the AB2-AuNP nanoreagent offered a limit of detection as low as 100 CFU mL-1. We have demonstrated the use of the AB2-AuNPs for detection of bacteria from environmental water samples.

Origin of Enhancement of Orbital Magnetic Moment in SiO2-Coated Fe3O4 Nanocomposites Studied by X-ray Magnetic Circular Dichroism.

In this study, magnetic Fe3O4 nanoparticles (NPs) were dispersed uniformly by varying the thickness of the SiO2 coating, and their electronic and magnetic properties were investigated. X-ray diffraction confirmed the structural configuration of monophase inverse-spinel Fe3O4 NPs in nanometer size. Scanning electron microscopy revealed the formation of proper nonporous crystallite particles with a clear core-shell structure with silica on the surface of Fe3O4 NPs. The absorption mechanism studied through the zeta potential indicates that SiO2-coated Fe3O4 nanocomposites (SiO2@Fe3O4 NCs) possess electrostatic interactions to control their agglomeration in stabilizing suspensions by providing a protective shield of amorphous SiO2 on the oxide surface. High-resolution transmission electron microscopy images demonstrate a spherical morphology having an average grain diameter of ∼11-17 nm with increasing thickness of SiO2 coating with the addition of a quantitative presence and proportion of elements determined through elemental mapping and electron energy loss spectroscopy studies. Synchrotron-based element-specific soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) techniques have been involved in the bulk-sensitive total fluorescence yield mode to understand the origin of magnetization in SiO2@Fe3O4 NCs. The magnetization hysteresis of Fe3O4 was determined by XMCD. At room temperature, the magnetic coercivity (Hc) is as high as 1 T, which is about 2 times more than the value of the thin film and about 5 times more pronounced than that of NPs. For noninteracting single-domain NPs with the Hc spread from 1 to 3 T, the Stoner-Wohlfarth model provided an intriguing explanation for the hysteresis curve. These curves determine the different components of Fe oxides present in the samples that derive the remnant magnetization involved in each oxidation state of Fe and clarify which Fe component is responsible for the resultant magnetism and magnetocrystalline anisotropy based on noninteracting single-domain particles.

Oxygen Plasma Induced Nanochannels for Creating Bimetallic Hollow Nanocrystals.

Platinum-based metal catalysts are considered excellent converters in various catalytic reactions, particularly in fuel cell applications. The atomic structure at the nanocrystal surface and the metal interface both influence the catalytic performance, controlling the efficiency of the electrochemical reactions. Here we report the synthesis of Ag/Pt and Ag/Pd core/shell nanocrystals and insight into the formation mechanism of these bimetallic core/shell nanocrystals when undergoing oxygen plasma treatment. We carefully designed the oxidation treatment that determines the structural and compositional evolution. The accelerated oxidation-triggered diffusion of Ag toward the outer metal shell leads to the Kirkendall effect. After prolonged oxygen plasma treatment, most core/shell nanocrystals evolve into hollow spheres. At the same time, a minor fraction of the metal remains unchanged with a well-protected Ag core and a monocrystalline Pt or Pd shell. We hypothesize that the O2 plasma disturbs the Pt or Pd shell surface and introduces active O species that react with the diffused Ag from the inside out. Based on EDX elemental mapping, combined with several electron microscopic techniques, we deduced the formation mechanism of the hollow structures to be as follows: (I) the oxidation of Ag within the Pt or Pd lattice causes a disrupted crystal lattice of Pt or Pd; (II) nanochannels arise at the defect locations on the Pt or Pd shell; (III) the remaining Ag atoms pass through these nanochannels and leave a hollow crystal behind. Our findings deepen the understanding of interface dynamics of bimetallic nanostructured catalysts under an oxidative environment and unveil an alternative approach for catalyst pretreatment.

Ultrathin Polypyrrole Layers Boosting MoO3 as Both Cathode and Anode Materials for a 2.0 V High-Voltage Aqueous Supercapacitor.

An aqueous supercapacitor is an emerging energy storage unit on account of its low cost, fast energy delivery rate, and long service life. The energy density of an aqueous supercapacitor can be enlarged via extending the voltage window of electrode materials, while the aqueous electrolyte remains thermodynamically constant at 1.23 V. Herein, an aqueous supercapacitor with a 2.0 V high-voltage window is realized by core-shell MoO3-x/polypyrrole (MP) nanocomposites as both cathode and anode materials. The ultrathin PPy layer on the MoO3 core not only improves the conductivity and cycle stability of the nanocomposites but also acts as a reductant, leading to the formation of oxygen vacancies in the MoO3 core. When used as a cathode material, the potential range of the as-obtained MP nanocomposite is up to 1.0 V. As an anode material, the stable potential range could reach -1.0 V. Due to the large potential range of the cathode and anode, the as-obtained 2.0 V aqueous supercapacitor shows a remarkably high delivery energy of 58.5 Wh kg-1. The synthesis of MP nanocomposites is simple and the electrode performance is significantly enhanced; thus, it is a suitable candidate for high-energy-density aqueous supercapacitors.

Highly Stretchable, Fast Self-Healing, and Waterproof Fluorinated Copolymer Ionogels with Selectively Enriched Ionic Liquids for Human-Motion Detection.

The development of waterproof ionogels with high stretchability and fast self-healing performance is essential for stretchable ionic conductors in sophisticated skin-inspired wearable sensors but can be rarely met in one material. Herein, a semicrystalline fluorinated copolymer ionogel (SFCI) with extremely high stretchability, underwater stability, and fast self-healability was fabricated, among which hydrophobic ionic liquids ([BMIM][TFSI]) were selectively enriched in fluoroacrylate segment domains of the fluorinated copolymer matrix through unique ion-dipole interactions. Benefiting from the reversible ion-dipole interactions between the [BMIM][TFSI] and fluoroacrylate segment domains as well as the physical cross-linking effects of semicrystalline oligoethylene glycol domains, the SFCI exhibited ultrastretchability (>6000%), fast room-temperature self-healability (>96% healing efficiency after cutting and self-healing for 30 min), and outstanding elasticity. In addition, the representative SFCI also exhibited high-temperature tolerance up to 300 °C, antifreezing performance as low as -35 °C, and high transparency (>93% visible-light transmittance). As a result, the as-obtained SFCI can readily be used as a highly stretchable ionic conductor in skin-inspired wearable sensors with waterproof performance for real-time detecting physiological human activities. These attractive features illustrate that the developed ultrastretchable and rapidly self-healable ionogels with unique waterproofness are promising candidates especially for sophisticated wearable strain sensing applications in complex and extreme environments.

Nanoporous Gold Bowls: A Kinetic Approach to Control Open Shell Structures and Size-Tunable Lattice Strain for Electrocatalytic Applications.

Controlling sub-10 nm ligament sizes and open-shell structure in nanoporous gold (NPG) to achieve strained lattice is critical in enhancing catalytic activity, but it remains a challenge due to poor control of reaction kinetics in conventional dealloying approach. Herein, a ligament size-controlled synthesis of open-shell NPG bowls (NPGB) through hetero-epitaxial growth of NPGB on AgCl is reported. The ligament size in NPGB is controlled from 6 to 46 nm by varying the hydroquinone to HAuCl4 ratio. The Williamson-Hall analysis demonstrates a higher lattice strain in smaller ligament size. In particular, NPGB with 6 nm (NPGB 6) ligament size possess the highest strain of 15.4 × 10(-3) , which is nearly twice of conventional 2D NPG sheets (≈8.8 × 10(-3) ). The presence of high surface energy facets in NPGBs is also envisaged. The best electrocatalytic activity toward methanol oxidation is observed in NPGB 6 (27.8 µA µg(-1) ), which is ≈9-fold and 3-fold higher than 8 nm solid Au nanoparticles, and conventional NPG sheets. The excellent catalytic activity in NPGB 6 is attributed to the open-shell structure, lattice strain, and higher electro-active surface area, allowing efficient exposure of catalytic active sites to facilitate the methanol oxidation. The results offer a potential strategy for designing next generation electrocatalysts.

Polydopamine-coated electrospun poly(vinyl alcohol)/poly(acrylic acid) membranes as efficient dye adsorbent with good recyclability.

Free-standing poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) membranes with polydopamine (PDA) coating were prepared based on the combination of electrospinning and self-polymerization of dopamine. This is a facile, mild, controllable, and low-energy consumption process without any rigorous restriction to reactive conditions. Benefiting from the high specific surface area of electrospun membranes and the abundant "adhesive" functional groups of polydopamine, the as-prepared membranes exhibit efficient adsorption performance towards methyl blue with the adsorption capacity reaching up to 1147.6 mg g(-1). Moreover, compared to other nanoparticle adsorbents, the as-prepared self-standing membrane is highly flexible, easy to operate and retrieve, and most importantly, easy to elute, and regenerate, which enable its potential applications in wastewater treatment.

Anisotropic conductive films based on highly aligned polyimide fibers containing hybrid materials of graphene nanoribbons and carbon nanotubes.

Anisotropic electrically conductive films (PI-GNR/CNT) consisting of highly aligned polyimide (PI) composite fibers with graphene nanoribbon (GNR) and carbon nanotube (CNT) (GNR/CNT) hybrids as nanofillers have been prepared by electrospinning. The GNR/CNT hybrids used here were prepared by one-step partial unzipping of multi-walled CNTs, in which, with the residual CNTs bonded on the randomly arranged GNR sheets, not only the aggregation of GNR sheets was greatly prevented but also an electrically conductive pathway with good conductivity was effectively formed with the CNTs acting as linking bridges between different GNRs. Due to the three-dimensional (3D) conductive network structure of the GNR/CNT hybrid and fine dispersion and alignment inside the PI fibers, as well as the good interfacial interaction between the GNR/CNT hybrid and the PI matrix, PI-GNR/CNT composite films exhibit a unique property of anisotropic electrical conductivity of 8.3 × 10(-2) S cm(-1) in the parallel direction along the fibers and 7.2 × 10(-8) S cm(-1) in the perpendicular direction, which may open the way for wide potential applications of anisotropic conductive nanomaterials in practical production and scientific research fields.

One-step synthesis of zero-dimensional hollow nanoporous gold nanoparticles with enhanced methanol electrooxidation performance.

Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.

Synthesis of few-layered MoS2 nanosheet-coated electrospun SnO2 nanotube heterostructures for enhanced hydrogen evolution reaction.

In this work, we report the fabrication of low crystalline, few-layered MoS2 nanosheet-coated electrospun SnO2 nanotube (MoS2/SnO2) heterostructures with three-dimensional configurations by electrospinning combined with a one-step solvothermal approach. The morphologies and compositions of the as-prepared hybrid nanotubes were characterized by field-emission scanning electron microscopy, transmission electron microscopy, ICP-AES, BET method, X-ray diffraction and X-ray photoelectron spectroscopy. Results show that SnO2 nanotubes are uniformly covered by sheet-like MoS2 subunits on both outer and inner surfaces. The electrocatalytic activity of MoS2/SnO2 heterostructures towards a hydrogen evolution reaction was examined using linear sweep voltammetry and AC impedance measurements. It is shown that the MoS2/SnO2 modified electrode exhibits excellent catalytic activity for hydrogen evolution with low overpotential, a small Tafel slope and high current density.

Electrospun carbon nanofibers decorated with Ag-Pt bimetallic nanoparticles for selective detection of dopamine.

Electrospun nanoporous carbon nanofibers (pCNFs) decorated with Ag-Pt bimetallic nanoparticles have been successfully synthesized by combining template carbonization and seed-growth reduction approach. Porous-structured polyacrylonitrile (PAN) nanofibers (pPAN) were first prepared by electrospinning PAN/polyvinylpyrrolidone (PVP) blend solution, followed by subsequent water extraction and heat treatment to obtain pCNFs. Ag-Pt/pCNFs were then obtained by using pCNFs as support for bimetallic nanoparticle loading. Thus, the obtained Ag-Pt/pCNFs were used to modify glassy carbon electrode (GCE) for selective detection of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA). This novel sensor exhibits fast amperometric response and high sensitivity toward DA with a wide linear concentration range of 10-500 µM and a low detection limit of 0.11 µM (S/N = 3), wherein the interference of UA and AA can be eliminated effectively.

Precision synthesis: designing hot spots over hot spots via selective gold deposition on silver octahedra edges.

A major challenge in plasmonic hot spot fabrication is to efficiently increase the hot spot volumes on single metal nanoparticles to generate stronger signals in plasmon-enhanced applications. Here, the synthesis of designer nanoparticles, where plasmonic-active Au nanodots are selectively deposited onto the edge/tip hot spot regions of Ag nanoparticles, is demonstrated using a two-step seed-mediated precision synthesis approach. Such a "hot spots over hot spots" strategy leads to an efficient enhancement of the plasmonic hot spot volumes on single Ag nanoparticles. Through cathodoluminescence hyperspectral imaging of these selective edge gold-deposited Ag octahedron (SEGSO), the increase in the areas and emission intensities of hot spots on Ag octahedra are directly visualized after Au deposition. Single-particle surface-enhanced Raman scattering (SERS) measurements demonstrate 10-fold and 3-fold larger SERS enhancement factors of the SEGSO as compared to pure Ag octahedra and non-selective gold-deposited Ag octahedra (NSEGSO), respectively. The experimental results corroborate well with theoretical simulations, where the local electromagnetic field enhancement of our SEGSO particles is 15-fold and 1.3-fold stronger than pure Ag octahedra and facet-deposited particles, respectively. The growth mechanisms of such designer nanoparticles are also discussed together with a demonstration of the versatility of this synthetic protocol.

Flexible polyaniline-coated TiO2/SiO2 nanofiber membranes with enhanced visible-light photocatalytic degradation performance.

A simple and practical strategy has been developed for preparing polyaniline (PANi) coated TiO2/SiO2 nanofiber membranes by a combination of electrospinning, calcination and in situ polymerization. TiO2/SiO2 (TS) nanofibers are fabricated by electrospinning, followed by calcination. Then they are used as template for in situ polymerization of aniline monomers. SEM images show that PANi nanoparticles thus formed can be densely and uniformly coated on the surface of TS nanofibers. Photocatalytic degradation tests show that the as-prepared nanofiber membranes exhibit enhanced photocatalytic activity for degradation of methyl orange under visible light, which may be due to the synergistic effect of PANi and TiO2. Furthermore, the effect of polymerization time on the morphology and photocatalytic activity of the membrane is investigated. The free-standing membrane is flexible and easy to handle, which is promising for potential applications in photocatalysis and water remediation fields.

One-step synthesis of graphene nanoribbon-MnO2 hybrids and their all-solid-state asymmetric supercapacitors.

Three-dimensional (3D) hierarchical hybrid nanomaterials (GNR-MnO2) of graphene nanoribbons (GNR) and MnO2 nanoparticles have been prepared via a one-step method. GNR, with unique features such as high aspect ratio and plane integrity, has been obtained by longitudinal unzipping of multi-walled carbon nanotubes (CNTs). By tuning the amount of oxidant used, different mass loadings of MnO2 nanoparticles have been uniformly deposited on the surface of GNRs. Asymmetric supercapacitors have been fabricated with the GNR-MnO2 hybrid as the positive electrode and GNR sheets as the negative electrode. Due to the desirable porous structure, excellent electrical conductivity, as well as high rate capability and specific capacitances of both the GNR and GNR-MnO2 hybrid, the optimized GNR//GNR-MnO2 asymmetric supercapacitor can be cycled reversibly in an enlarged potential window of 0-2.0 V. In addition, the fabricated GNR//GNR-MnO2 asymmetric supercapacitor exhibits a significantly enhanced maximum energy density of 29.4 W h kg(-1) (at a power density of 12.1 kW kg(-1)), compared with that of the symmetric cells based on GNR-MnO2 hybrids or GNR sheets. This greatly enhanced energy storage ability and high rate capability can be attributed to the homogeneous dispersion and excellent pseudocapacitive performance of MnO2 nanoparticles and the high electrical conductivity of the GNRs.

Nitrogen-doped graphene nanoribbons as efficient metal-free electrocatalysts for oxygen reduction.

Nitrogen-doped graphene nanoribbon (N-GNR) nanomaterials with different nitrogen contents have been facilely prepared via high temperature pyrolysis of graphene nanoribbons (GNR)/polyaniline (PANI) composites. Here, the GNRs with excellent surface integration were prepared by longitudinally unzipping the multiwalled carbon nanotubes. With a high length-to-width ratio, the GNR sheets are prone to form a conductive network by connecting end-to-end to facilitate the transfer of electrons. Different amounts of PANI acting as a N source were deposited on the surface of GNRs via a layer-by-layer approach, resulting in the formation of N-GNR nanomaterials with different N contents after being pyrolyzed. Electrochemical characterizations reveal that the obtained N8.3-GNR nanomaterial has excellent catalytic activity toward an oxygen reduction reaction (ORR) in an alkaline electrolyte, including large kinetic-limiting current density and long-term stability as well as a desirable four-electron pathway for the formation of water. These superior properties make the N-GNR nanomaterials a promising kind of cathode catalyst for alkaline fuel cell applications.

Highly sensitive nonenzymatic glucose and H2O2 sensor based on Ni(OH)2/electroreduced graphene oxide--multiwalled carbon nanotube film modified glass carbon electrode.

In this article, a nonenzymatic sensor based on Ni(OH)2/electroreduced graphene oxide (ERGO)-multiwalled carbon nanotube (MWNT) nanocomposites is fabricated via convenient electrodeposition of Ni(OH)2 nanoparticles on ERGO-MWNT film modified glass carbon electrode (GCE). Graphene oxide (GO) sheets can serve as surfactants to stabilize the dispersion of pristine MWNTs in aqueous solution, rendering a fine coverage of ERGO-MWNT film on GCE during the fabrication process. MWNTs perform as conducting bridges between ERGO sheets to enhance the electron transfer rate in the substrate. By combining the advantages of ERGO and MWNTs, together with electrocatalytic effect of Ni(OH)2 nanoparticles, the well-designed nanocomposites exhibit excellent sensing behavior towards glucose and hydrogen peroxide (H2O2). The linear detection ranges for glucose and H2O2 are 10-1500 µM and 10 µM-9050 µM while the detection limits are 2.7 µM and 4.0 µM, respectively. Furthermore, a very high sensitivity is achieved with 2042 µAm M(-1) cm(-2) estimated for glucose and 711 µAm M(-1) cm(-2) for H2O2. These results suggest that Ni(OH)2/ERGO-MWNT nanocomposites thus easily prepared through a green electrochemical method are promising electrode materials for biosensing. Additionally, good recoveries of analytes in real samples like urine and milk confirm the reliability of the prepared sensor in practical applications.

Bimetallic platonic Janus nanocrystals.

We demonstrate the creation of Ag-based bimetallic platonic Janus nanostructures by confining galvanic replacement reaction at a nanoscale interface on highly symmetrical nanostructures such as Ag nanocubes and nanooctahedra using reactive microcontact printing (µCP). The extent of galvanic replacement reaction can be controlled kinetically to derive Janus nanostructures with Au nanodots deposited on either one or multiple facets of Ag nanocubes. The selective deposition of Au dots on a single facet of Ag nanocubes breaks the cubic symmetry and brings about unique and anisotropic plasmonic responses. High-resolution cathodoluminescence hyperspectral imaging of single Janus nanocube demonstrates that surface plasmon resonances corresponding to Au and Ag can be excited at different spots on one Janus nanocube. In addition, we demonstrate the fabrication of alternating Janus/non-Janus segments on 2D Ag nanowires by using a line-patterned polydimethylsiloxane (PDMS) stamp for galvanic replacement. Aside from Au, Pt and Pd can also be selectively deposited onto Ag nanocubes. These Janus nanostructures may find important applications in the field of plasmon-enhanced catalysis.

Magnetic nanomaterial derived from graphene oxide/layered double hydroxide hybrid for efficient removal of methyl orange from aqueous solution.

Magnetic hybrid nanomaterials composed of reduced graphene oxide, zero-valent nickel, and NiAl-mixed metal oxides (rGO/Ni/MMO) have been synthesized by calcining graphene oxide (GO)/layered double hydroxide (LDH) hybrid in nitrogen atmosphere. Structural characterizations demonstrate that with the presence of GO substrate, NiAl-LDHs can be reduced into zero-valent Ni and NiAl-MMOs during calcination. Transmission electron microscopy (TEM) is used to investigate the morphology of the as-prepared hybrid nanomaterials, demonstrating that the introduction of GO substrate prevents the aggregation of LDHs. Magnetism characterization proves the ferromagnetic property of rGO/Ni/MMO hybrid. This magnetic hybrid nanomaterial exhibits excellent adsorption ability toward methyl orange (MO) in aqueous solutions. The kinetics of the adsorption process and the adsorption isotherm are investigated. The MO removal process is found to obey the Redlich-Peterson isotherm model, and its kinetics follows pseudo-second-order rate equation. In addition, the magnetic hybrid also exhibits good recycle ability for MO removal. This novel magnetic hybrid nanomaterial derived from GO/LDH hybrid demonstrates great potential in the applications of water treatment.

Hierarchical composites of polyaniline-graphene nanoribbons-carbon nanotubes as electrode materials in all-solid-state supercapacitors.

A three dimensional (3D) polyaniline (PANI)-graphene nanoribbon (GNR)-carbon nanotube (CNT) composite, PANI-GNR-CNT, has been prepared via in situ polymerization of an aniline monomer on the surface of a GNR-CNT hybrid. Here, the 3D GNR-CNT hybrid has been conveniently prepared by partially unzipping the pristine multi-walled CNTs, while the residual CNTs act as "bridges" connecting different GNRs. The morphology and structure of the resulting hybrid materials have been characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD). Electrochemical tests reveal that the hierarchical PANI-GNR-CNT composite based on the two-electrode cell possesses much higher specific capacitance (890 F g(-1)) than the GNR-CNT hybrid (195 F g(-1)) and neat PANI (283 F g(-1)) at a discharge current density of 0.5 A g(-1). At the same time, the PANI-GNR-CNT composite displays good cycling stability with a retention ratio of 89% after 1000 cycles, suggesting that this novel PANI-GNR-CNT composite is a promising candidate for energy storage applications.