Engineered Molecular Chain Ordering in Single‐Walled Carbon Nanotubes/Polyaniline Composite Films for High‐Performance Organic Thermoelectric Materials

Single‐walled carbon nanotubes (SWNTs)/polyaniline (PANI) composite films with enhanced thermoelectric properties were prepared by combining in situ polymerization and solution processing. Conductive atomic force microscopy and X‐ray diffraction measurements confirmed that solution processing and strong π–π interactions between the PANI and SWNTs induced the PANI molecules to form a highly ordered structure. The improved degree of order of the PANI molecular arrangement increased the carrier mobility and thereby enhanced the electrical transport properties of PANI. The maximum in‐plane electrical conductivity and power factor of the SWNTs/PANI composite films reached 1.44×10³ S cm^?1 and 217 μW m^?1 K^?2, respectively, at room temperature. Furthermore, a thermoelectric generator fabricated with the SWNTs/PANI composite films showed good electric generation ability and stability. A high power density of 10.4 μW cm^?2 K^?1 was obtained, which is superior to most reported results obtained in organic thermoelectric modules.     

Bis(tert‐butylpyrene) Nanotweezers and Nanocalipers: Enhanced Extraction and Recognition Abilities for Single‐Walled Carbon Nanotubes

We developed a host–guest methodology for separation of single‐walled carbon nanotubes (SWNTs) according to the handedness, diameter and metallicity by the use of diporphyrin nanotweezers and nanocalipers. Although the pyrene has been frequently used to replace porphyrin, due to a similar affinity to the surface of SWNTs and better availability, the extraction and recognition abilities of dipyrene nanotweezers were not so good as those of diporphyrin ones as we reported previously. However, introduction of a tert‐butyl substituent at the 7′‐position of 2‐pyrene is found to enhance the extraction and recognition abilities of dipyrene nanotweezers and nanocalipers. That is, (6,5)‐SWNTs were obtained in high purity by use of bis(tert‐butylpyrene) nanotweezers with a phenanthrene spacer and metallic SWNTs were highly enriched by use of bis(tert‐butylpyrene) nanocalipers with a carbazole–anthracene–carbazole spacer.     

Rapid One‐Step Synthesis and Compaction of High‐Performance n‐Type Mg3Sb2 Thermoelectrics

n‐type Mg₃Sb₂‐based compounds have emerged as a promising class of low‐cost thermoelectric materials due to their extraordinary performance at low and intermediate temperatures. However, so far, high thermoelectric performance has merely been reported in n‐type Mg₃Sb₂‐Mg₃Bi₂ alloys with a large amount of Bi. Moreover, current synthesis methods of n‐type Mg₃Sb₂ bulk thermoelectrics involve multi‐step processes that are time‐ and energy‐consuming. Herein, we report a fast and straightforward approach to fabricate n‐type Mg₃Sb₂ thermoelectrics using spark plasma sintering, which combines the synthesis and compaction in one step. Using this method, we achieve a high thermoelectric figure of merit zT of about 0.4–1.5 at 300–725 K in n‐type (Sc, Te)‐co‐doped Mg₃Sb₂ without alloying with Mg₃Bi₂. In comparison with the currently reported synthesis methods, the complexity, process time, and cost of our method are significantly reduced. This work demonstrates a simple, low‐cost route for the potential large‐scale production of n‐type Mg₃Sb₂ thermoelectrics.     

Selective and Scalable Chemical Removal of Thin Single‐Walled Carbon Nanotubes from their Mixtures with Double‐Walled Carbon Nanotubes

Double‐walled carbon nanotubes (DWCNTs) are materials in high demand due to their superior properties. However, it is very challenging to prepare DWCNTs samples of high purity. In particular, the removal of single‐walled carbon nanotubes (SWCNTs) contaminants is a major problem. Here, a procedure for a selective removal of thin‐diameter SWCNTs from their mixtures with DWCNTs by lithium vapor treatment is investigated. The results are evaluated by Raman spectroscopy and in situ Raman spectroelectrochemistry. It is shown that the amount of SWCNTs was reduced by about 35 % after lithium vapor treatment of the studied SWCNTs–DWCNTs mixture.     

Synthesis and Platinum Complexes of an Alane‐Appended 1,1′‐Bis(phosphino)ferrocene Ligand

An aryldimethylalane‐appended analogue of 1,1′‐bis(diphenylphosphino)ferrocene, FcPPAl, was prepared, and reaction with [Pt(nb)₃] (nb=norbornene) afforded [Pt(η²‐nb)(FcPPAl)] ( 1 ). Heating a solution of 1 to 80 °C resulted in crystallization of [{Pt(FcPPAl)}₂] ( 2 ), whereas treatment of 1 with C₂H₄, C₂Ph₂, H₂, or CO provided [PtL(FcPPAl)] [L=C₂H₄ ( 3 ), C₂Ph₂ ( 4 )], [PtH₂(FcPPAl)] ( 5 ), and [Pt(CO)(FcPPAl)] ( 6 ). In all complexes, the FcPPAl ligand is coordinated through both phosphines and the alane. Whereas 2 adopts a T‐shaped geometry at platinum, 3 – 5 are square‐pyramidal, and 6 is distorted square‐planar. The hydride and carbonyl complexes feature unusual multicenter bonding involving platinum, aluminum, and a hydride or carbonyl ligand.     

Covalent Attachment of Anderson‐Type Polyoxometalates to Single‐Walled Carbon Nanotubes Gives Enhanced Performance Electrodes for Lithium Ion Batteries

Single‐walled carbon nanotubes (SWNTs) covalently functionalized with redox‐active organo‐modified polyoxometalate (POM) clusters have been synthesized and employed as electrode materials in lithium ion batteries. The Anderson cluster [MnMo₆O₂₄]^9? is functionalized with Tris (NH₂C(CH₂OH)₃) moieties, giving the new organic–inorganic hybrid [N(nC₄H₉)₄]₃[MnMo₆O₁₈{(OCH₂)₃CNH₂}₂]. The compound is then covalently attached to carboxylic acid‐functionalized SWNTs by amide bond formation and the stability of this nanocomposite is confirmed by various spectroscopic methods. Electrochemical analyses show that the nanocomposite displays improved performance as an anode material in lithium ion batteries compared with the individual components, that is, SWNTs and/or Anderson clusters. High discharge capacities of up to 932 mAh g^?1 at a current density of 0.5 mA cm^?2 can be observed, together with high long‐term cycling stability and decreased electrochemical impedance. Chemisorption of the POM cluster on the SWNTs is shown to give better electrode performance than the purely physisorbed analogues.     

Electrochemical Behavior and Determination of L‐Tyrosine at Single‐walled Carbon Nanotubes Modified Glassy Carbon Electrode

Based on single‐walled carbon nanotubes (SWCNTs) modified glassy carbon electrode (GCE/SWCNTs), a novel method was presented for the determination of L ‐tyrosine. The GCE/SWCNTs exhibited remarkable catalytic and enhanced effects on the oxidation of L ‐tyrosine. In 0.10 mol/L citric acid‐sodium citrate buffer solution, the oxidation potential of L ‐tyrosine shifted negatively from +1.23 V at bare GCE to +0.76 V at GCE/SWCNTs. Under the optimized experimental conditions, the linear range of the modified electrode to the concentration of L ‐tyrosine was 5.0×10^?6–2.0×10^?5 mol/L (R₁=0.9952) and 2.7×10^?5–2.6×10^?4 mol/L (R₂=0.9998) with a detection limit of 9.3×10^?8 mol/L. The kinetic parameters such as α (charge transfer coefficient) and D (diffusion coefficient) were evaluated to be 0.66, 9.82×10^?5 cm² s^?1, respectively. And the electrochemical mechanism of L ‐tyrosine was also discussed.     

Platinum Complexes of a Borane‐Appended Analogue of 1,1′‐Bis(diphenylphosphino)ferrocene: Flexible Borane Coordination Modes and in situ Vinylborane Formation

A bis(phosphine)borane ambiphilic ligand, [Fe(η⁵‐C₅H₄PPh₂)(η⁵‐C₅H₄PtBu{C₆H₄(BPh₂)‐ortho})] (FcPPB), in which the borane occupies a terminal position, was prepared. Reaction of FcPPB with tris(norbornene)platinum(0) provided [Pt(FcPPB)] ( 1 ) in which the arylborane is η³BCC‐coordinated. Subsequent reaction with CO and CNXyl (Xyl=2,6‐dimethylphenyl) afforded [PtL(FcPPB)] {L=CO ( 2 ) and CNXyl ( 3 )} featuring η²BC‐ and η¹B‐arylborane coordination modes, respectively. Reaction of 1 or 2 with H₂ yielded [PtH(μ‐H)(FcPPB)] in which the borane is bound to a hydride ligand on platinum. Addition of PhC₂H to [Pt(FcPPB)] afforded [Pt(C₂Ph)(μ‐H)(FcPPB)] ( 5 ), which rapidly converted to [Pt(FcPPB′)] ( 6 ; FcPPB′=[Fe(η⁵‐C₅H₄PPh₂)(η⁵‐C₅H₄PtBu{C₆H₄(BPh‐CPh=CHPh‐Z)‐ortho}]) in which the newly formed vinylborane is η³BCC‐coordinated. Unlike arylborane complex 1 , vinylborane complex 6 does not react with CO, CNXyl, H₂ or HC₂Ph at room temperature.     

Preparation of Single‐Handed Helical Carbon/Silica and Carbonaceous Nanotubes by Using 4,4′‐Biphenylene‐Bridged Polybissilsesquioxane

Single‐handed, helical, 4,4′‐biphenylene‐bridged polybissilsesquioxane nanotubes were prepared by using the self‐assemblies of a pair of chiral low‐molecular‐weight gelators as templates. Single‐handed, helical, carbon/silica nanotubes were obtained after carbonization of the self‐assemblies, and single‐handed helical carbonaceous nanotubes were then obtained by removal of silica with aqueous HF. Samples were characterized by using field‐emission SEM, TEM, X‐ray diffraction, thermogravimetric analysis, Raman spectroscopy, and circular dichroism. The polysilsesquioxane and carbonaceous structures exhibited optical activity. The walls of the carbon/silica and carbonaceous nanotubes were predominantly amorphous carbon. The surface area of the left‐handed, helical, carbonaceous nanotubes was 1439 m² g^?1, and such materials have potential applications as catalyst supports, chirality sensors, supercapacitor electrodes, and adsorbents.     

Carbon Nanotubes Fed on “Carbs”: Coating of Single‐Walled Carbon Nanotubes by Dextran Sulfate

A facile and easily reproducible technique for assembling biohybrid nanoparticles is a core feature that is highly desired for biomedical applications, considering the nature and limited lifespan of the biopolymers used. Here we show a simple and effective method to enfold single‐walled carbon nanotubes (SWNTs) using an anionic polysaccharide, dextran sulfate. After their interactions, SWNTs were rendered dispersible in aqueous solution and were shortened and unbundled to their basic dimension. Atomic force microscopy analysis was extensively employed to elucidate the mechanism of their interfacing. This biohybrid nanoparticle holds promise for biological and biomedical applications due to the synergistic unique properties of SWNTs and dextran sulfate.

     

Extraction of (9,8) Single‐Walled Carbon Nanotubes by Fluorene‐Based Polymers

Selective polymer wrapping is a promising approach to obtain high‐chiral‐purity single‐walled carbon nanotubes (SWCNTs) needed in technical applications and scientific studies. We showed that among three fluorene‐based polymers with different side‐chain lengths and backbones, poly[(9,9‐dihexylfluorenyl‐2,7‐diyl)‐co‐(9,10‐anthracene)] (PFH‐A) can selectively extract SWCNTs synthesized from the CoSO₄/SiO₂ catalyst, which results in enrichment of 78.3 % (9,8) and 12.2 % (9,7) nanotubes among all semiconducting species. These high‐chiral‐purity SWCNTs may find potential applications in electronics, optoelectronics, and photovoltaics. Furthermore, molecular dynamics simulations suggest that the extraction selectivity of PFH‐A relates to the bending and alignment of its alkyl chains and the twisting of its two aromatic backbone units (biphenyl and anthracene) relative to SWCNTs. The strong π–π interaction between polymers and SWCNTs would increase the extraction yield, but it is not beneficial for chiral selectivity. Our findings suggest that the matching between the curvature of SWCNTs and the flexibility of the polymer side chains and the aromatic backbone units is essential in designing novel polymers for selective extraction of (n,m) species.     

A Mercury Iodide Adduct with 1,1‐Bis(diphenylphosphino)ferrocene – Synthesis,Crystal Structure,and Nonlinear Refractive Properties

A new mercury iodide complex of dppf, [HgI₂(dppf)] (adduct 1 , dppf = 1,1‐bis(diphenylphosphino)ferrocene) was prepared and characterized. Single crystal X‐ray diffraction analysis established that the compound crystallizes in the monoclinic system, space group C2c, with a = 34.992(3), b = 10.236(5), c = 18.765(4) Å, β = 99.410(2)°, Z = 8, V = 6631.2(9) ų. The coordination about the mercury atom is tetrahedral with two equivalent Hg–I and Hg–P bonds. Dppf functions as a chelating ligand. The nonlinear optical (NLO) properties were studied with an 8 ns‐pulsed laser at 532 nm. Its optical responses to the incident light exhibit weak optical absorptive and strong refractive effects, with n₂ = 6.86 × 10^–18 m² · W^–1 in a 2.48 × 10^–4 mol · dm^–3 DMF solution.     

Covalent and Non‐covalent Chemical Modification of Multi‐walled Carbon Nanotubes with Tetra‐(4‐hydroxylphenyl)porphyrin and Its Complexes

Multi‐walled carbon nanotubes (MWNTs) were covalently and non‐covalently functionalized with tetra‐(4‐hydroxylphenyl) porphyrin (THPPH₂) and its complexes (ZnTHPP) forming dispersible nanohybrids in organic solution. The morphology of the nanohybrids was observed with transmission electron microscopy. The structure of the product was characterized by FT‐IR, UV‐Vis spectrophotometer, fluorescence spectroscopy and thermogravimetric analysis. The photo‐induced electron‐transfer process of the nanohybrids in organic solution was also revealed.     

Electrocatalytic Oxidation of Diethylaminoethanethiol and Hydrazine at Single‐walled Carbon Nanotubes Modified with Prussian Blue Nanoparticles

In this work, edged plane pyrolytic graphite electrode EPPGE was modified with functionalised single‐walled carbon nanotubes and Prussian blue nanoparticles (PB). The modified electrode was characterised by techniques such as TEM, FTIR, XPS, EDX and cyclic voltammetry. The EPPGE‐SWCNT‐PB platform exhibited enhanced electron transport and catalytic efficiency towards the oxidation of Diethylaminoethanethiol (DEAET) and hydrazine compared with the other electrodes studied. The EPPGE‐SWCNT‐PB showed good electrochemical stability in the analytical solution, showing limit of detection in the micromolar range and catalytic rate constant of 3.71×10⁶ and 7.56×10⁶ cm³ mol^?1 s^?1 for DEAET and hydrazine respectively. The adsorption properties of these analytes that impact on their detection at the SWCNT‐PB film modified electrode were evaluated and discussed.     

Synthesis of Platinum and Tin Oxide Co‐functionalized Single‐walled Carbon Nanotubes (Pt/SnO2/SWNTs) and their Sensing Properties toward Carbon Monoxide

Pt and SnO₂ were co‐functionalized on single‐walled carbon nanotubes (SWNTs) assembled on microelectrodes by electrochemical deposition where Pt nanoparticle's morphology, size, and density were tuned by controlling the applied potential and time. The systematic study to obtain the optimum condition for Pt‐decorated SnO₂/SWNTs (Pt/SnO₂/SWNTs) were performed and also correlate with its CO sensing performance. Illumination‐dependent sensing performance was examined using red, green and UV LED as light sources at room temperature. Under UV illumination, the sensitivity of Pt/SnO₂/SWNTs was enhanced to 2.1 %/ppm_V of CO with the lower detection limit of 0.05 ppm_V.