Nanostructured Hybrid Materials Research Articles

Platinum-free counter electrodes of plasma-modified hybrid nanomaterials for dye-sensitised solar cells

ABSTRACTMolybdenum disulphide (MoS2) nanotube and tungsten oxide (W18O49) nanowire were coated with poly(3-hexylthiophene) (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT) by a radio frequency (RF: 13.56 MHz)-rotating plasma-modification method as alternative counter electrodes for dye-sensitised solar cells (DSSCs). Surface analysis showed the homogenous plasma nanocoating of inorganic nanostructures by P3HT and PEDOT. It was demonstrated that the plasma-modified hybrid platinum-free counter electrodes increased the efficiencies of the DSSCs. The DSSCs based on hybrid nanostructure materials showed a short circuit current density of 9.49, 7.95, 2.59 and 2.57 mAcm−2 for MoS2/P3HT, MoS2/PEDOT, W18O49/PEDOT and W18O49/P3HT samples, respectively. The plasma nanocoating with the nanostructured materials approach for obtaining hybrid counter electrodes in the photovoltaic action shows an alternative route towards cost-effective, green energy conversion.

Superhydrophobic properties induced by sol-gel routes on copper surfaces

Superhydrophobic surfaces are attracting increasing attention in different fields such as energy, transportation, building industry and electronics, as they exhibit many interesting properties such as high water repellence, anti-fogging, anti-corrosion, anti-fouling and self-cleaning abilities. Here, superhydrophobic nanostructured hybrid materials obtained by depositing alumina nanoparticles on copper surfaces via dip coating in Al2O3 sol are presented. Two different preparation routes were explored, based on either an alcoholic or an aqueous Al2O3 sol, and the resulting wetting properties were compared. Wettability measurements showed that when the alcoholic sol is used superhydrophobicity is attained, with values of water contact angle very close to the upper limit of 180°, while highly hydrophobic coatings are obtained with the aqueous sol. These findings were further supported by electron microscopy and X-ray photoelectron spectroscopy, which revealed that the surface layer deposited on Cu is more homogenous and richer in alumina nanoparticles when the alcoholic sol was used. Durability of the superhydrophobic coating was assessed by performing ageing tests in chemically aggressive environments. A remarkable resistance is displayed by the superhydrophobic coating in acid environment, while alkaline conditions severely affect its properties. Such behaviors were investigated by XPS and FE-SEM measurements, which disclosed the nature of the surface reactions under the different conditions tested. The present results underline that a thorough investigation of surface morphology, chemical composition and wetting properties reveals their strongly connection and helps optimizing the combination of substrate nanostructuring and suitable chemical coating for an improved durability in different aggressive environments.

Nanostructured carbon supported Pd-ceria as anode catalysts for anion exchange membrane fuel cells fed with polyalcohols

In this manuscript we present a new anode catalyst, a Pd-CeO2/C hybrid nanostructured material composed of nanostructured Pd and nanostructured CeO2 supported on C for direct polyalcohol fuel cells. This material fully characterized by HR-TEM, XRD, Raman spectroscopy, TGA and surface area determination techniques (BET and Chemisorption) is studied for the electrooxidation of ethylene glycol and 1,2-propanediol in electrochemical half cells and complete AEM-FCs. At a cell temperature of 60°C peak power densities of around 50mWcm−2 are obtained compared to 20–25mWcm−2 for an equivalent Pd/C catalyst. For the first time the energy efficiency of such fuel cells has been determined with a value of 2% obtained for the cell fed with 1,2-propandiol. All oxidation products for each fuel have been identified and quantified using HPLC and NMR spectroscopy. From ethylene glycol 80% of glycolate is formed while from 1,2-propandiol 58% of lactate is formed. Both of these compounds are key industrial chemicals.

(Industrial Electrochemistry and Electrochemical Engineering Division H. H. Dow Memorial Student Achievement Award Address) Electrochemically Active Hybrid Materials for Pseudocapacitive Energy Storage

Electrochemically active hybrid materials are an emerging class of materials for both small and large-scale electrochemical energy storage applications. The possibility of nanoscale engineering inorganic and organic components in a unique hybrid material provides new and sometimes exceptional sets of properties, which makes them attractive for a variety of applications.1 While organic/inorganic hybrid nanomaterials exhibit tremendous potential for the pseudocapacitive energy storage, the choice of an optimal organic material and nanostructured inorganic support impedes their energy storage applications.2 We will present the exciting development of pseudocapacitive hybrid materials for both static and flowable energy storage systems.3–7 Our approach includes a combination of suitable redox active organic molecules with various types of carbon nanostructures and/or highly conductive metal carbides (MXenes).8 These combinations improve conductivity, resulting in high energy and power density pseudocapacitive electrodes with improved cycling performance. Using experimental techniques and molecular simulations, we will discuss the interfacial organic-inorganic interactions, charge storage mechanisms, and preferred molecular orientations of organic molecules at the interface. Remaining challenges and future opportunities for improvement in nanostructured hybrid materials for the electrochemical energy storage will be highlighted. 1. H. Wang and H. Dai, Chem. Soc. Rev., 42, 3088–3113 (2013) 2. D. Vonlanthen, P. Lazarev, K. a. See, F. Wudl, and A. J. Heeger, Adv. Mater., 26, 5095–5100 (2014). 3. M. Boota et al., Adv. Mater., 28, 1517–22 (2015) 4. M. Boota, K. B. Hatzell, E. C. Kumbur, and Y. Gogotsi, ChemSusChem, 8, 835–843 (2015). 5. M. Boota, C. Chen, M. Bécuwe, L. Miao, and Y. Gogotsi, Energy Environ. Sci., 9, 2586–2594 (2016). 6. M. Boota et al., ChemSusChem, 8, 3576–3581 (2015) 7. K. B. Hatzell, M. Boota, and Y. Gogotsi, Chem. Soc. Rev., 44, 8664–8687 (2015) 8. M. Naguib, V. N. Mochalin, M. W. Barsoum, and Y. Gogotsi, Adv. Mater., 26, 992–1005 (2014)

Redox-Active Hybrid Materials for Pseudocapacitive Energy Storage

We aim to show the exciting development of sustainable pseudocapacitive hybrid materials for small and large scale electrochemical energy storage systems.1–5 In our approach, we combine redox-active organic molecules with suitable carbon nanostructures and/or highly conductive metal carbides (MXenes) to improve the conductivity of organic materials. These combinations result in high energy and power density pseudocapacitive electrodes with improved cyclability. Using experimental and simulation techniques, we will discuss the interfacial organic-inorganic interactions, charge storage mechanisms, and preferred molecular orientations of organic molecules at the interface. We will also highlight the remaining challenges and future opportunities for improvement in nanostructured hybrid materials for the electrochemical energy storage. 1. M. Boota et al., Adv. Mater., 28, 1517–22 (2015) 2. M. Boota, K. B. Hatzell, E. C. Kumbur, and Y. Gogotsi, ChemSusChem, 8, 835–843 (2015). 3. M. Boota, C. Chen, M. Bécuwe, L. Miao, and Y. Gogotsi, Energy Environ. Sci., 9, 2586–2594 (2016). 4. M. Boota et al., ChemSusChem, 8, 3576–3581 (2015) 5. K. B. Hatzell, M. Boota, and Y. Gogotsi, Chem. Soc. Rev., 44, 8664–8687 (2015)

Visible-Light-Active TiO2-Based Hybrid Nanocatalysts for Environmental Applications

Photocatalytic nanomaterials such as TiO2 are receiving a great deal of attention owing to their potential applications in environmental remediation. Nonetheless, the low efficiency of this class of materials in the visible range has, so far, hampered their large-scale application. The increasing demand for highly efficient, visible-light-active photocatalysts can be addressed by hybrid nanostructured materials in which two or more units, each characterised by peculiar physical properties, surface chemistry and morphology, are combined together into a single nano-object with unprecedented chemical–physical properties. The present review intends to focus on hybrid nanomaterials, based on TiO2 nanoparticles able to perform visible-light-driven photocatalytic processes for environmental applications. We give a brief overview of the synthetic approaches recently proposed in the literature to synthesise hybrid nanocrystals and discuss the potential applications of such nanostructures in water remediation, abatement of atmospheric pollutants (including NOx and volatile organic compounds (VOCs)) and their use in self-cleaning surfaces.

Dual‐Confined Sulfur in Hybrid Nanostructured Materials for Enhancement of Lithium‐Sulfur Battery Cathode Capacity Retention

AbstractHerein, we report a dual‐confined sulfur cathode with a nanostructure where sulfur (72.5 wt %) is first encapsulated in microporous carbon (MC) cores and embedded by graphene (G) shells. Larger and soluble polysulfide intermediates (Li2Sx, 4≤x≤8) are trapped by the graphene shells and thus to refrain from dissolution into the organic electrolyte, so that a stable cycling performance can be achieved. Moreover, the graphene shell and hollow space in‐between also help to ensure the integrity of the hybrid cathode against the volume expansion upon cycling. On the other hand, MC confines smaller sulfur molecules (S2‐4) within its small pores and suppresses the formation of soluble polysulfides. The resulting electrode delivers a high initial discharge capacity of 982 mAh g−1 with enhanced capacity retention of 85.4 % after 100th cycles at 0.2 C rates. More importantly, it exhibits a high discharge capacity of 886 mAh g−1, which is maintained at 601 mAh g−1 after 500 cycles at 0.5 C with a coulombic efficiency of nearly 100 %, which is the best performance among reported cycle stabilities.

Nanostructured hybrid materials as precursors of mesoporous NiMo-based catalysts for the propane oxidative dehydrogenation

Nanostructured hybrid materials made of guest ions and a self-assembled copolymer were used as precursors for the preparation of NiMo-based catalysts. The hybrids were calcined in air and the recovered materials were characterized and tested in propane oxidative dehydrogenation. A 6-fold improvement of the yield to propene is obtained as compared with classically prepared catalysts. The exothermic degradation profile of the copolymer is the key point of our approach as it allows to prepare a porous β-NiMoO4, namely the phase particularly desired for its superior propene selectivity. More precisely, the polar backbone and the aliphatic side chains of the copolymer burn at different temperatures. The former ignites at moderate temperatures and initiates the early crystallization of β-NiMoO4. Occurring at higher temperature, the decomposition of the aliphatic part then induces the formation of mesopores. A β-NiMoO4 can thus be prepared at moderate temperatures whereas elevated calcination temperatures (>650 °C) are usually required. This peculiar behavior enables to prevent the texture of NiMoO4 from sintering and to maintain at high levels its mesoporosity, specific area and thus catalytic activity. At the end, the use of our tailor designed copolymer template allows reaching the remarkably high propene yields obtained.

Long-Lasting Nb2O5-Based Nanocomposite Materials for Li-Ion Storage.

Advanced nanostructured hybrid materials can help us overcome the electrochemical performance limitations of current energy storage devices. In this study, three-dimensional porous carbon nanowebs (3D-CNWs) with numerous included orthorhombic Nb2O5 (T-Nb2O5) nanoparticles were fabricated using a microbe-derived nanostructure. The 3D-CNW/T-Nb2O5 nanocomposites showed an exceptionally stable long-term cycling performance over 70 000 cycles, a high reversible capacity of ∼125 mA h g-1, and fast Li-ion storage kinetics in a coin-type two-electrode system using Li metal. In addition, energy storage devices based on the above nanocomposites achieved a high specific energy of ∼80 W h kg-1 together with a high specific power of ∼5300 W kg-1 and outstanding cycling performance with ∼80% capacitance retention after 35 000 cycles.

Evidence for the contribution of degenerate hydrogen atom transport to the persistence of sulfanyl radicals anchored to nanostructured hybrid materials

Nanostructured functionalized silicas were used as a platform to compare the behaviour of anchored arylsulfanyl radicals depending on the nature of their precursors.

Photoinduced nanostructured organosilica hybrids

Organosilane self-assembly is an efficient way to synthesize nanostructured hybrid materials. The key parameters of the process are based on selecting appropriate precursor architecture (mono-, bis- or multi-sylilated organosilane) under adapted sol–gel reaction and processing conditions. The general mechanism of this template-free process relies on the generation of amphiphilic species that can self-assemble and cross-link subsequently by siloxane Si-O-Si condensation. Self-organization results thus from an interplay between enthalpic and entropic contribution. Recently, we demonstrated the potential of the photoinduced synthesis and ordering of nanostructured hybrids as an original and attractive route to afford well-condensed organosilicate films. This work will review the driving forces of this approach encompassing the structure of the organosilane precursor, thermodynamic and kinetic parameters.

Ultrafine Cobalt Sulfide Nanoparticles Encapsulated Hierarchical N-doped Carbon Nanotubes for High-performance Lithium Storage

Nanostructured cobalt sulfide based materials with rational design are attractive for high-performance lithium-ion batteries. In this work, we report a multistep method to synthesize ultrafine cobalt sulfide nanoparticles encapsulated in hierarchical N-doped carbon nanotubes (CoSx@HNCNTs). Co-based zeolitic imidazolate framework (ZIF-67) nanotubes are obtained from the reaction between electrospun polyacrylonitrile/cobalt acetate and 2-methylimidazole, followed by the dissolution of template. Next, a combined calcination and sulfidation process is employed to convert the ZIF-67 nanotubes to CoSx@HNCNTs. Benefited from the compositional and structural features, the as-prepared nanostructured hybrid materials deliver superior lithium storage properties with high capacity of 1200mAhg−1 at 0.25Ag−1. More importantly, a remarkable capacity of 1086mAhg−1 can be maintained after 100 cycles at the current density of 0.5Ag−1. Even at a high rate of 5Ag−1, a reversible capacity of 592mAhg−1 after 1600 cycles can still be achieved.

Electroosmotic Flow in Mixed Polymer Brush-Grafted Nanochannels.

Mixed polymer brush-grafted nanochannels—where two distinct species of polymers are alternately grafted on the inner surface of nanochannels—are an interesting class of nanostructured hybrid materials. By using a coarse-grained molecular dynamics simulation method, we are able to simulate the electrokinetic transport dynamics of the fluid in such nanochannels as well as the conformational behaviors of the mixed polymer brush. We find that (1) the brush adopts vertically-layered and longitudinally-separated structures due to the coupling of electroosmotic flow (EOF) and applied electric field; (2) the solvent quality affects the brush conformations and the transport properties of the EOF; (3) the EOF flux non-monotonically depends on the grafting density, although the EOF velocity in the central region of the channel monotonically depends on the grafting density.

The Effect of Hydrophobicity on the Synthesis of Homogeneous and Nanostructured NiMo-Based Hybrid Materials

Nanostructured hybrid materials made of guest ions and a polyampholytic self-assembled copolymer are here synthesized. Their lamellar organization results from hydrophobic interactions between the copolymer alkyl side chains. Longer side chains improve the organization of hybrids what makes them more attractive to be used as a template for the preparation of sophisticated catalysts. However, they also enhance the hydrophobicity of the copolymer what complicates the synthesis of such hybrids. Dodecyl side chains appear as a compromise that enables to prepare well organized hybrids without sacrificing the copolymer capacity to link ions.

Colloidal Assembly of Hierarchically Structured Porous Supraparticles from Flower-Shaped Protein-Inorganic Hybrid Nanoparticles.

Mimicry of biomineralization is an attractive strategy to fabricate nanostructured hybrid materials. While biomineralization involves processes that organize hybrid clusters into complex structures with hierarchy, arrangement of artificial components in biomimetic approaches has been challenging. Here, we demonstrate self-assembly of hierarchically structured porous supraparticles from protein-inorganic hybrid flower-shaped (FS) nanoparticle building blocks. In our strategy, the FS nanoparticles self-assemble via high valency interactions in combination with interfacial adsorption and compression. The flower-like shape directed robust assembly of the FS nanoparticles into chain-like clusters in solution, which were further assembled into spherical supraparticles during rotation of FS nanoparticle solution. Continuously expanding and contracting the air-water interface during rotation catalyzed assembly of FS nanoparticle clusters, indicating that adsorption and compression of the building blocks at the interface were critical. The resulting supraparticles contain hierarchical pores which are translated from the structural characteristics of individual FS nanoparticle building blocks. The protein-inorganic supraparticles are protein-compatible, have large surface area, and provide specific affinity recognition for robust protein immobilization. A variety of functional proteins could be immobilized to the porous supraparticles, making it a general platform that could provide benefits for many applications.

Facile synthesis of rod-like nanostructured histidine-phosphomolybdate hybrid material with microemulsion method

ABSTRACT A new rod-like nanostructured Keggin-type amino acid-polyoxometalate hybrid material, (His)3PMo12O40 (His = histidine), was synthesized using nonionic microemulsion method. The water pools in the microemulsion system acted as nanoreactors for the reaction of histidinium hydrochloride and phosphomolybdic acid to produce nanostructured (His)3PMo12O40 hybrid material. A stoichiometric amount of histidinium ion as an organic species was substituted in the Keggin-type heteropoly acid, while its primary structure remained intact. The structural characterizations indicated the nanosized rod-like morphology of the product with the average diameter size of about 100 nm.

Synergistic Assembly of Peptide-Metal Hydroxide Hybrid Nanostructures for Electrochemical Capacitors

Electrochemical deposition of metal hydroxide in presence of peptide amphiphile results self-assembled nanoscale hybrid thin films. We demonstrate here the self-assembly of three small aromatic peptides (NmYW, NmFW and NmFY) with three transition metal hydroxides (Co(OH)2, Ni(OH)2 and Zn(OH)2). Here peptides are used as structure directing agent for the construction of organic/inorganic hybrid nanostructured materials. Electrodeposition of different peptide/metal hydroxides is carried out potentoiodynamically applying constant potential using indium tin oxide (ITO) as working electrode. Scanning electron microscopy (SEM) is used to visualize the surface morphology of peptide/metal hydroxide thin films. The interactions among peptides and peptides-metal hydroxides are exhibited using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. Electrochemical measurements are performed to examine the energy storage behavior of peptide/metal hydroxide nanohybrids. Porous nanostructure of peptide/Co(OH)2 hybrid shows high capacitance of 3070 Fg-1 through electron transfer mechanism in the potential range -0.2 to 0.6 V at discharge current of 5 mA. Soft and porous nanostructure facilitates the electrochemical accessibility of electrolyte OH- ions to Co(OH)2 thin films and fast diffusion rate within the redox phase. This study provides a useful platform for the construction of various electrochemically active peptide/metal hydroxide nanoscale hybrid materials which exhibit capacitive electrochemical performance in energy storage applications.

Functional twin monomers and twin macro monomers as components for the synthesis of hierarchically nanostructured hybrid materials*

Functional twin monomers and twin macro monomers as components for the synthesis of hierarchically nanostructured hybrid materials*

Nanostructured MoS2 Nanorose/Graphene Nanoplatelet Hybrids for Electrocatalysis.

Tailoring and enhancing electrocatalytic activity is of the utmost importance from the viewpoints of sustainable energy and sensing. MoS2 and graphene show great promise for the electrocatalysis of many reactions. Given that both graphene and MoS2 are highly anisotropic in nature, with edge planes that are several orders of magnitude more catalytically active than basal planes, a new hybrid material with maximized edge-plane density to provide efficient electron transfer, high catalytic activity, and conductive cores was engineered. The hybrid material consists of radial MoS2 nanosheets with a high density of edge planes and unsaturated active sulfur atoms as well as interspersed with conductive graphene nanoplatelets. This hybrid material exhibits excellent activity for the hydrogen evolution reaction and the detection of DNA nucleobases. Such a nanoengineered, nanostructured hybrid material may play a major role in future electrocatalytic devices.

Core–shell structured Na3V2(PO4)3/C nanocrystals embedded in multi-walled carbon nanotubes: A high-performance cathode for sodium-ion batteries

In this work, we study the synthesis and electrochemical performance of Na3V2(PO4)3/C and multi-walled carbon nanotubes (MWCNTs) hybrid nanocomposite for use as cathode material in high performance sodium-ion batteries. This nanostructured hybrid material is prepared through a hydrothermal-assisted sol–gel process followed by thermal annealing. The obtained sample has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectrum. The crosslinked MWCNTs can provide good electronic conductive pathways interconnecting Na3V2(PO4)3/C particles. Electrode fabricated from this hybrid material delivers a high reversible capacity and superior rate performance up to an extremely high rate of 10C. Moreover, ultralong cycling stability is also attained through 500cycles at 10C with 93.9% capacity retention. These results demonstrate that the addition of MWCNTs is an effective way to improve the electrochemical performance of Na3V2(PO4)3/C cathode material for sodium-ion batteries.