General Interfacial Self‐Assembly Engineering for Patterning Two‐Dimensional Polymers with Cylindrical Mesopores on Graphene

Free‐standing 2D porous nanomaterials have attracted considerable interest as ideal candidates of 2D film electrodes for planar energy storage devices. Nevertheless, the construction of well‐defined mesopore arrays parallel to the lateral surface, which facilitate fast in‐plane ionic diffusion, is a challenge. Now, a universal interface self‐assembly strategy is used for patterning 2D porous polymers, for example, polypyrrole, polyaniline, and polydopamine, with cylindrical mesopores on graphene nanosheets. The resultant 2D sandwich‐structured nanohybrids are employed as the interdigital microelectrodes for the assembly of planar micro‐supercapacitors (MSCs), which deliver outstanding volumetric capacitance of 102 F cm^?3 and energy density of 2.3 mWh cm^?3, outperforming most reported MSCs. The MSCs display remarkable flexibility and superior integration for boosting output voltage and capacitance.     

Electrochemical Synthesis of a Microporous Conductive Polymer Based on a Metal–Organic Framework Thin Film

A new approach to preparing 3D microporous conductive polymer has been demonstrated in the electrochemical synthesis of a porous polyaniline network with the utilization of a MOF thin film supported on a conducting substrate. The prepared porous polyaniline with well‐defined uniform micropores of 0.84 nm exhibits a high BET surface area of 986 m² g^?1 and a high electric conductivity of 0.125 S cm^?1 when doped with I₂, which is superior to existing porous conducting materials of porous MOFs, CMPs, and COFs.     

Synthesis of Two‐dimensional Microporous Carbonaceous Polymer Nanosheets and Their Application as High‐performance CO2 Capture Sorbent

The synthesis of two‐dimensional (2D) polymer nanosheets with a well‐defined microporous structure remains challenging in materials science. Here, a new kind of 2D microporous carbonaceous polymer nanosheets was synthesized through polymerization of a very low concentration of 1,4‐dicyanobenzene in molten zinc chloride at 400–500 °C. This type of nanosheets has a thickness in the range of 3–20 nm, well‐defined microporosity, a high surface area (～537 m² g^?1), and a large micropore volume (～0.45 cm³ g^?1). The microporous carbonaceous polymer nanosheets exhibit superior CO₂ sorption capability (8.14 wt % at 298 K and 1 bar) and a relatively high CO₂ selectivity toward N₂ (25.6). Starting from different aromatic nitrile monomers, a variety of 2D carbonaceous polymer nanosheets can be obtained showing a certain universality of the ionothermal method reported herein.     

High‐Conductivity Two‐Dimensional Polyaniline Nanosheets Developed on Ice Surfaces

A new method to develop two‐dimensional PANI nanosheets using ice as a removable hard template is presented. Distinctly high current flows of 5.5 mA at 1 V and a high electrical conductivity of 35 S cm^?1 were obtained for the polyaniline (PANI) nanosheets, which marked a significant improvement from previously values on other PANIs reported over the past decades. These improved electrical properties of ice‐templated PANI nanosheets were attributed to the long‐range ordered edge‐on π‐stacking of the quinoid ring, ascribed to the ice surface‐assisted vertical growth of PANI. The unprecedented advantages of the ice‐templated PANI nanosheets are two‐fold. First, the PANI nanosheet can be easily transferred onto various types of substrates via float‐off from the ice surfaces. Second, PANI can be patterned into any shape using predetermined masks, and this is expected to facilitate the eventual convenient and inexpensive application of conducting polymers in versatile electronic device forms.     

Confined Self‐Assembly in Two‐Dimensional Interlayer Space: Monolayered Mesoporous Carbon Nanosheets with In‐Plane Orderly Arranged Mesopores and a Highly Graphitized Framework

Although two‐dimensional (2D) carbon materials are widely investigated, a well‐defined 2D carbon nanosheet with an ordered mesostructure has rarely been realized. Monolayer‐ordered mesoporous carbon nanosheets (OMCNS) were prepared through confinement assembly of resol and F127 in the interlayer of montmorillonite (MONT). The nanoscale distance of the interlayer space of MONT only allow the assembly of resol and F127 in the same plane, leading to ordered mesopores perpendicular to carbon nanosheets, and favor the formation of sp² carbon, resulting in a high degree of graphitization. The mesopores on the carbon nanosheets provide efficient ion diffusion, and the high degree of graphitization provides a fast electron‐transport route, enabling OMCNS as excellent electrode materials for electric double layer capacitors.     

Large‐Area,Free‐Standing,Two‐Dimensional Supramolecular Polymer Single‐Layer Sheets for Highly Efficient Electrocatalytic Hydrogen Evolution

The rational construction of covalent or noncovalent organic two‐dimensional nanosheets is a fascinating target because of their promising applications in electronics, membrane technology, catalysis, sensing, and energy technologies. Herein, a large‐area (square millimeters) and free‐standing 2D supramolecular polymer (2DSP) single‐layer sheet (0.7–0.9 nm in thickness), comprising triphenylene‐fused nickel bis(dithiolene) complexes has been readily prepared by using the Langmuir–Blodgett method. Such 2DSPs exhibit excellent electrocatalytic activities for hydrogen generation from water with a Tafel slope of 80.5 mV decade^?1 and an overpotential of 333 mV at 10 mA cm^?2, which are superior to that of recently reported carbon nanotube supported molecular catalysts and heteroatom‐doped graphene catalysts. This work is promising for the development of novel free‐standing organic 2D materials for energy technologies.     

Importance of domain purity in semi‐conducting polymer/insulating polymer blends transistors

Printed electronics is a rapidly developing field of research which covers any electronic devices or circuits that can be processed using direct printing techniques. Among those printing techniques, inkjet printing is a technique of increasing interest for organic field‐effect transistors (FETs) due to its fully data driven and direct patterning. In this work, the morphology of semi‐conducting polymer/insulating polymer blends from inkjet printing and their FET properties have been investigated. We attempted to optimize the morphology of the blends by the addition of a co‐solvent to the blend solution prior to film deposition. By varying the boiling temperature of the co‐solvent, blend films are fabricated with varying domain purity and different degree of semi‐conducting polymer ordering. The morphologies of all the as‐cast samples from inkjet printing and subsequently thermally annealed samples are characterized by grazing incidence wide angle x‐ray scattering and small angle neutron scattering. The results indicate that the sample where a low boiling temperature co‐solvent is used exhibits a lower degree of semi‐conducting polymer ordering and less pure domains, resulting in a decrease of hole mobility. The morphologies that are formed when high boiling temperature co‐solvent is used, however, give a higher degree of semi‐conducting polymer ordering along with higher domain purity, significantly improving hole mobility up to 1.44 cm² V^?1 s^?1 at V_DS = 40 V. More importantly, with thermal annealing, all the samples exhibit similar semi‐conducting polymer ordering and domain sizes while the domain purity significantly varies. This work is a unique example that demonstrates the importance of domain purity in the optimization of morphology and FET performance, which is previous unavailable. It also provides a novel process that can efficiently control the morphology of semi‐conducting polymer/insulating polymer mixtures during deposition to maximize FET performance from inkjet printing. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1760–1766     

Ultrathin Metal–Organic Framework Nanosheets with Ultrahigh Loading of Single Pt Atoms for Efficient Visible‐Light‐Driven Photocatalytic H2 Evolution

A surfactant‐stabilized coordination strategy is used to make two‐dimensional (2D) single‐atom catalysts (SACs) with an ultrahigh Pt loading of 12.0 wt %, by assembly of pre‐formed single Pt atom coordinated porphyrin precursors into free‐standing metal–organic framework (MOF) nanosheets with an ultrathin thickness of 2.4±0.9 nm. This is the first example of 2D MOF‐based SACs. Remarkably, the 2D SACs exhibit a record‐high photocatalytic H₂ evolution rate of 11 320 μmol g^?1 h^?1 via water splitting under visible light irradiation (λ>420 nm) compared with those of reported MOF‐based photocatalysts. Moreover, the MOF nanosheets can be readily drop‐casted onto solid substrates, forming thin films while still retaining their photocatalytic activity, which is highly desirable for practical solar H₂ production.     

Formation and Geometrical Control of Polygon‐Like Metal‐Coordination Assemblies

Polygon‐like [2+2]‐ and [3+3]‐type metal complexes were prepared from dipyrrin dimers connected by acute‐angled spacers. The electrical conduction depends strongly on the packing alignment of the compounds, revealing the presence of effective hopping pathways for holes with relatively high mobility up to 0.11 cm² V^?1 s^?1 along the aligned axis of [3+3]‐type metal‐bridged assemblies. These observations correlated with the geometrical control of the π‐conjugated metal complexes in the cyclic structures, which enables their ordered arrangement in the assemblies.     

Electro‐optical properties of electropolymerized poly(3‐hexylthiophene)/carbon nanotube composite thin films

3‐hexylthiophene was electropolymerized on a carbon nanotube (CNT)‐laden fluorine‐doped tin oxide substrate. Scanning electron microscopy and Raman spectroscopy revealed that the polymer was infused throughout the thickness of the 150‐nm thick CNT mat, resulting in a conducting composite film with a dense CNT network. The electropolymerized poly(3‐hexylthiophene) (e‐P3HT)/CNT composites exhibited photoluminescence intensity quenching by as much as 92% compared to the neat e‐P3HT, which provided evidence of charge transfer from the polymer phase to the CNT phase. Through‐film impedance and J‐V measurements of the composites gave a conductivity (σ) of 1.2 × 10^?10 S cm^?1 and zero‐field mobility (μ₀) of 8.5 × 10^?4 cm² V^?1 s^?1, both of which were higher than those of neat e‐P3HT films (σ = 9.9 × 10^?12 S cm^?1, μ₀ = 3 × 10^?5 cm² V^?1 s^?1). In electropolymerized samples, the thiophene rings were oriented in the (010) direction (thiophene rings parallel to substrate), which resulted in a broader optical absorbance than for spin coated samples, however, the lack of long‐range conjugation caused a blueshift in the absorbance maximum from 523 nm for unannealed regioregular P3HT (rr‐P3HT) to 470 nm for e‐P3HT. Raman spectroscopy revealed that π‐π stacking in e‐P3HT was comparable to that in rr‐P3HT and significantly higher than in regiorandom P3HT (ran‐P3HT) as shown by the principal Raman peak shift from 1444 to 1446 cm^?1 for e‐P3HT and rr‐P3HT to 1473 cm^?1 for ran‐P3HT. This work demonstrates that these polymer/CNT composites may have interesting properties for electro‐optical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1269–1275, 2011     

Self‐Assembly of MXene‐Surfactants at Liquid–Liquid Interfaces: From Structured Liquids to 3D Aerogels

2D transition metal carbides and nitrides (MXenes), a class of emerging nanomaterials with intriguing properties, have attracted significant attention in recent years. However, owing to the highly hydrophilic nature of MXene nanosheets, assembly strategies of MXene at liquid–liquid interfaces have been very limited and challenging. Herein, through the cooperative assembly of MXene and amine‐functionalized polyhedral oligomeric silsesquioxane at the oil–water interface, we report the formation, assembly, and jamming of a new type MXene‐based Janus‐like nanoparticle surfactants, termed MXene‐surfactants (MXSs), which can significantly enhance the interfacial activity of MXene nanosheets. More importantly, this simple assembly strategy opens a new platform for the fabrication of functional MXene assemblies from mesoscale (e.g., structured liquids) to macroscale (e.g., aerogels), that can be used for a range of applications, including nanocomposites, electronic devices, and all‐liquid microfluidic devices.     

3D Assembly of All‐Inorganic Colloidal Nanocrystals into Gels and Aerogels

We report an efficient approach to assemble a variety of electrostatically stabilized all‐inorganic semiconductor nanocrystals (NCs) by their linking with appropriate ions into multibranched gel networks. These all‐inorganic non‐ordered 3D assemblies benefit from strong interparticle coupling, which facilitates charge transport between the NCs with diverse morphologies, compositions, sizes, and functional capping ligands. Moreover, the resulting dry gels (aerogels) are highly porous monolithic structures, which preserve the quantum confinement of their building blocks. The inorganic semiconductor aerogel made of 4.5 nm CdSe colloidal NCs capped with I^? ions and bridged with Cd²⁺ ions had a large surface area of 146 m² g^?1.     

Electrochemical Exfoliation of Pillared‐Layer Metal–Organic Framework to Boost the Oxygen Evolution Reaction

Two‐dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal–organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared‐layer framework. When the 3D pillared‐layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal–organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm^?2 and a turnover frequency as high as 30 s^?1 at an overpotential of 300 mV.     

Nanoimprint Lithography‐Directed Self‐Assembly of Bimetallic Iron–M (M=Palladium,Platinum) Complexes for Magnetic Patterning

Self‐assembly of d⁸ metal polypyridine systems is a well‐established approach for the creation of 1D organometallic assemblies but there are still challenges for the large‐scale construction of nanostructured patterns from these building blocks. We describe herein the use of high‐throughput nanoimprint lithography (NIL) to direct the self‐assembly of the bimetallic complexes [4′‐ferrocenyl‐(2,2′:6′,2′′‐terpyridine)M(OAc)]⁺(OAc)^? (M=Pd or Pt; OAc=acetate). Uniform nanorods are fabricated from the molecular self‐organization and evidenced by morphological characterization. More importantly, when top‐down NIL is coupled with the bottom‐up self‐assembly of the organometallic building blocks, regular arrays of nanorods can be accessed and the patterns can be controlled by changing the lithographic stamp, where the mold imposes a confinement effect on the nanorod growth. In addition, patterns consisting of the products formed after pyrolysis are studied. The resulting arrays of ferromagnetic FeM alloy nanorods suggest promising potential for the scalable production of ordered magnetic arrays and fabrication of magnetic bit‐patterned media.     

Large‐Area,Free‐Standing,Two‐Dimensional Supramolecular Polymer Single‐Layer Sheets for Highly Efficient Electrocatalytic Hydrogen Evolution

The rational construction of covalent or noncovalent organic two‐dimensional nanosheets is a fascinating target because of their promising applications in electronics, membrane technology, catalysis, sensing, and energy technologies. Herein, a large‐area (square millimeters) and free‐standing 2D supramolecular polymer (2DSP) single‐layer sheet (0.7–0.9 nm in thickness), comprising triphenylene‐fused nickel bis(dithiolene) complexes has been readily prepared by using the Langmuir–Blodgett method. Such 2DSPs exhibit excellent electrocatalytic activities for hydrogen generation from water with a Tafel slope of 80.5 mV decade⁻¹ and an overpotential of 333 mV at 10 mA cm⁻², which are superior to that of recently reported carbon nanotube supported molecular catalysts and heteroatom‐doped graphene catalysts. This work is promising for the development of novel free‐standing organic 2D materials for energy technologies.     

Interfacial synthesis of crystalline quasi-two-dimensional polyaniline thin films for high-performance flexible on-chip micro-supercapacitors

Quasi-two-dimensional (q2D) conducting polymer thin film synergizes the advantageous features of long-range molecular ordering and high intrinsic conductivity, which are promising for flexible thin film-based micro-supercapacitors (MSCs). Herein, we present the high-performance flexible MSCs based on highly ordered quasi-two-dimensional polyaniline (q2D-PANI) thin film using surfactant monolayer assisted interfacial synthesis (SMAIS). Owing to high electrical conductivity, rich redox chemistry, and thin-film morphology, the q2D-PANI MSCs show high volumetric specific capacitance (ca. 360 F/cm³) and energy density (17.9 mWh/cm³), which outperform the state-of-art PANI thin-film based MSCs and promise for future flexible electronics.     

Synthesis and characterization of novel nano size electroactive poly 4,4′‐diaminodiphenyl sulphone

The modification of electrodeposited polyaniline film by subsequent electrodeposition of 4,4′‐diaminodiphenyl sulfone (DDS) leads to a new material having nanostructure. The coated polymer films were treated with various pH solutions. The film adherent characteristics and surface morphology were studied using SEM. The electrochemically synthesized polyDDS revealed good redox behavior. The DDS was also polymerized by the chemical oxidation method using potassium persulphate. The polymer was characterized by UV‐Vis and FTIR spectral studies. The formation of polymer through the N? H group was understood from the single N? H stretching vibrational frequency at 3459 cm^?1. The X‐ray diffraction studies revealed the formation of nano sized (28 nm) crystalline polymer. The conductivity of the polymer was determined to be 1.07 × 10^?4 S.cm^?1. The solubility of the chemically polymerized powder was ascertained, and polyDDS showed good solubility in DMF and DMSO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1702–1707, 2005     

2D Confined‐Space Assisted Growth of Molecular‐Level‐Thick Polypyrrole Sheets with High Conductivity and Transparency

Herein, the use of a 2D soft template system composed of hundred‐nanometer‐thick water/ethanol mixed layers sandwiched by lamellar bilayer membranes of a self‐assembled amphiphilic molecule to produce ultrathin polyprrole (PPy) with a uniform thickness as thin as 3.8 nm and with large dimensions (>2 μm²) is presented. The obtained PPy nanosheets exhibit regioregularity with ordered chain alignment where the polymer chains in the nanosheets produced are well aligned with a clear interchain spacing as confirmed by small‐angle X‐ray scattering measurement. The molecular‐level‐thick PPy nanosheets exhibit extremely high conductivity up to 1330 S m⁻¹, thanks to the ordered alignment of polymer chains in the nanosheets, and a high transparency in both the visible region (transmittance >99%) and near‐infrared region (transmittance >93%).

     

Hierarchical Micro‐Mesoporous Carbon‐Framework‐Based Hybrid Nanofibres for High‐Density Capacitive Energy Storage

Advanced methods, allowing the controllable synthesis of ordered structural nanomaterials with favourable charges transfer and storage, are highly important to achieve ideal supercapacitors with high energy density. Herein, we report a microliter droplet‐based method to synthesize hierarchical‐structured metal–organic framework/graphene/carbon nanotubes hybrids. The confined ultra‐small‐volume reaction, give well‐defined hybrids with a large specific‐surface‐area (1206 m² g^?1), abundant ionic‐channels (narrow pore of 0.86 nm), and nitrogen active‐sites (10.63 %), resulting in high pore‐size utilization (97.9 %) and redox‐activity (32.3 %). We also propose a scalable microfluidic‐blow‐spinning method to consecutively generate nanofibre‐based flexible supercapacitor electrodes with striking flexibility and mechanical strength. The supercapacitors display large volumetric energy density (147.5 mWh cm^?3), high specific capacitance (472 F cm^?3) and stably deformable energy‐supply.     

Metal‐Folded Single‐Chain Nanoparticle: Nanoclusters and Self‐Assembled Reduction‐Responsive Sub‐5‐nm Discrete Subdomains

Easy access to discrete nanoclusters in metal‐folded single‐chain nanoparticles (metal‐SCNPs) and independent ultrafine sudomains in the assemblies via coordination‐driven self‐assembly of hydrophilic copolymer containing 9% imidazole groups is reported herein. ¹H NMR, dynamic light scattering, and NMR diffusion‐ordered spectroscopy results demonstrate self‐assembly into metal‐SCNPs (>70% imidazole‐units folded) by neutralization in the presence of Cu(II) in water to pH 4.6. Further neutralization induces self‐assembly of metal‐SCNPs (pH 4.6–5.0) and shrinkage (pH 5.0–5.6), with concurrent restraining residual imidazole motifs and hydrophilic segment, which organized into constant nanoparticles over pH 5.6–7.5. Atomic force microscopy results evidence discrete 1.2 nm nanoclusters and sub‐5‐nm subdomains in metal‐SCNP and assembled nanoparticle. Reduction of metal center using sodium ascorbate induces structural rearrangement to one order lower than the precursor. Enzyme mimic catalysis required media‐tunable discrete ultrafine interiors in metal‐SCNPs and assemblies have hence been achieved.