Photosensitizer Encryption with Aggregation Enhanced Singlet Oxygen Production.

Chromophores that generate singlet oxygen (1O2) in water are essential to developing noninvasive disease treatments using photodynamic therapy (PDT). A facile approach for formation of stable colloidal nanoparticles of 1O2 photosensitizers, which exhibit aggregation enhanced 1O2 generation in water toward applications as PDT agents, is reported. Chromophore encryption within a fuchsonarene macrocyclic scaffold insulates the photosensitizer from aggregation induced deactivation pathways, enabling a higher chromophore density than typical 1O2 generating nanoparticles. Aggregation enhanced 1O2 generation in water is observed, and variation in molecular structure allows for regulation of the physical properties of the nanoparticles which ultimately affects the 1O2 generation. In vitro activity and the ability of the particles to pass through the cell membrane into the cytoplasm is demonstrated using confocal fluorescence microscopy with HeLa cells. Photosensitizer encryption in rigid macrocycles, such as fuchsonarenes, offers new prospects for the production of biocompatible nanoarchitectures for applications involving 1O2 generation.

Self-Powered Sensors and Flexible Triboelectric Nanogenerator for Powering Portable Electronics.

We report on a flexible triboelectric nanogenerator (FTENG) designed using polydimethylsiloxane (PDMS) and aluminium (Al) combinations to convert ambient mechanical energy into electrical outputs. An open-circuit output voltage of ~40 V and short-circuit current density of ~63.6 mA m-2 with power density 0.62 W m-2 was easily obtained from the FTENG. The harvested mechanical energy is used for lighting ~100 light emitting diodes and to operate seven segment display enabling prospects for carbon-emission free environment friendly source for powering portable electronic devices. We have shown the capability of using the FTENG as self-powered weight and pressure sensors. Additionally, flexible design of the FTENG extends its application scope for self-powered tactile sensing in electronic skin for robotic application. The FTENG is simply designed, cost-effective, scalable and high-throughput for possible uses in flexible electronics, self-powered systems and body sensor networks.

Induced Aggregation of AIE-Active Mono-Cyclometalated Ir(III) Complex into Supramolecular Branched Wires for Light-Emitting Diodes.

Aggregation-induced emission (AIE) is commonly observed in irregular bulk form. Herein, unique aggregation properties of an AIE-active complex into branched supramolecular wires are reported for the first time. Mono-cyclometalated Ir(III) complex shows in-plane J-aggregation at the air-water interface owing to the restriction of intramolecular vibration of bidentate phenylpyridinato and intramolecular rotations of monodentate triphenylphosphine ligands at air-water interface. As a consequence, a large enhancement of luminescence comparable to the solid state is obtained from the monolayers of supramolecular wires. This unique feature is utilized for the fabrication of light-emitting diodes with low threshold voltage using supramolecular wires as active layer. This study opens up the need of ordered assembly of AIE complexes to achieve optimal luminescence characteristics.

Self-oriented ß-crystalline phase in the polyvinylidene fluoride ferroelectric and piezo-sensitive ultrathin Langmuir-Schaefer film.

We report on the direct observation of ferroelectric switching and piezoelectric behaviour in ultrathin polyvinylidene fluoride (PVDF) films prepared by horizontal Langmuir-Schaefer (LS) technique. We have prepared pure ß-phase by just increasing the number of LS layers without using additional non-ferroelectric assisting agents. Edge-on oriented CH2-CF2 units of PVDF at the air-water interface enable self-orientation of ferroelectric dipoles by means of the hydrogen bonding network. Such restricted conformation of PVDF at the air-water interface results in an increased net dipole moment with the number of LS layers. The film's ferroelectric switching and piezoelectric sensitivity are demonstrated by hysteretic polarization switching loops and butterfly-loops, respectively. Successful circular domain writing on ultrathin LS film, down to 5 monolayers of PVDF, is demonstrated. The achievement of pure ß-phase of PVDF at room temperature without using any assisting agents may be promising for non-volatile memory and piezoelectric-based, ultrathin smart sensor devices.

Aligned 1-D nanorods of a π-gelator exhibit molecular orientation and excitation energy transport different from entangled fiber networks.

Linear π-gelators self-assemble into entangled fibers in which the molecules are arranged perpendicular to the fiber long axis. However, orientation of gelator molecules in a direction parallel to the long axes of the one-dimensional (1-D) structures remains challenging. Herein we demonstrate that, at the air-water interface, an oligo(p-phenylenevinylene)-derived π-gelator forms aligned nanorods of 340 ± 120 nm length and 34 ± 5 nm width, in which the gelator molecules are reoriented parallel to the long axis of the rods. The orientation change of the molecules results in distinct excited-state properties upon local photoexcitation, as evidenced by near-field scanning optical microscopy. A detailed understanding of the mechanism by which excitation energy migrates through these 1-D molecular assemblies might help in the design of supramolecular structures with improved charge-transport properties.

Improved mechanical stability of acetoxypropyl cellulose upon blending with ultranarrow PbS nanowires in Langmuir monolayer matrix.

Cellulose and cellulose derivatives have long been used as membrane fabrication. Langmuir monolayer behavior, which naturally mimics membranes, of acetoxypropyl cellulose (APC) and lead sulfide (PbS) nanowire mixtures at different volume ratios is reported. Surface pressure (π)-area (A) isotherms of APC and PbS nanowires mixtures at different volume ratios show a gradual decrease in the monolayer area with increasing volume fraction of PbS nanowires. Change of surface potential with monolayer area at different volume ratios also reveals a gradual increase in the surface potential indicating incorporation of PbS nanowires within APC matrix. The compressibility and elastic constants measurements reveal an enhancement of the elasticity upon incorporation of PbS nanowires up to certain volume fractions. An enhancement in stability of the blend is observed upon PbS nanowire incorporation to the APC matrix. Rheological measurements also support the robustness of the mixture of APC and PbS nanowires in 3D bulk phase. Such robust ultrathin films of cellulose based-nanowire blend obtained by means of the Langmuir technique may lead to novel routes for designing cellulosic-based thin films and membranes.

Measurement of Volatile Fatty Acids in Silage through Odors with Nanomechanical Sensors.

The measurement of volatile fatty acids (VFAs) is of great importance in the fields of food and agriculture. There are various methods to measure VFAs, but most methods require specific equipment, making on-site measurements difficult. In this work, we demonstrate the measurements of VFAs in a model sample, silage, through its vapor using an array of nanomechanical sensors-Membrane-type Surface stress Sensors (MSS). Focusing on relatively slow desorption behaviors of VFAs predicted with the sorption kinetics of nanomechanical sensing and the dissociation nature of VFAs, the VFAs can be efficiently measured by using features extracted from the decay curves of the sensing response, resulting in sufficient discrimination of the silage samples. Since the present sensing system does not require expensive, bulky setup and pre-treatment of samples, it has a great potential for practical applications including on-site measurements.

Nanoarchitectonics for Hierarchical Fullerene Nanomaterials.

Nanoarchitectonics is a universal concept to fabricate functional materials from nanoscale building units. Based on this concept, fabrications of functional materials with hierarchical structural motifs from simple nano units of fullerenes (C60 and C70 molecules) are described in this review article. Because fullerenes can be regarded as simple and fundamental building blocks with mono-elemental and zero-dimensional natures, these demonstrations for hierarchical functional structures impress the high capability of the nanoarchitectonics approaches. In fact, various hierarchical structures such as cubes with nanorods, hole-in-cube assemblies, face-selectively etched assemblies, and microstructures with mesoporous frameworks are fabricated by easy fabrication protocols. The fabricated fullerene assemblies have been used for various applications including volatile organic compound sensing, microparticle catching, supercapacitors, and photoluminescence systems.

Nelumbo nucifera Seed-Derived Nitrogen-Doped Hierarchically Porous Carbons as Electrode Materials for High-Performance Supercapacitors.

Biomass-derived activated carbon materials with hierarchically nanoporous structures containing nitrogen functionalities show excellent electrochemical performances and are explored extensively in energy storage and conversion applications. Here, we report the electrochemical supercapacitance performances of the nitrogen-doped activated carbon materials with an ultrahigh surface area prepared by the potassium hydroxide (KOH) activation of the Nelumbo nucifera (Lotus) seed in an aqueous electrolyte solution (1 M sulfuric acid: H2SO4) in a three-electrode cell. The specific surface areas and pore volumes of Lotus-seed-derived carbon materials carbonized at a different temperatures, from 600 to 1000 °C, are found in the range of 1059.6 to 2489.6 m2 g-1 and 0.819 to 2.384 cm3 g-1, respectively. The carbons are amorphous materials with a partial graphitic structure with a maximum of 3.28 atom% nitrogen content and possess hierarchically micro- and mesoporous structures. The supercapacitor electrode prepared from the best sample showed excellent electrical double-layer capacitor performance, and the electrode achieved a high specific capacitance of ca. 379.2 F g-1 at 1 A g-1 current density. Additionally, the electrode shows a high rate performance, sustaining 65.9% capacitance retention at a high current density of 50 A g-1, followed by an extraordinary long cycle life without any capacitance loss after 10,000 subsequent charging/discharging cycles. The electrochemical results demonstrate that Nelumbo nucifera seed-derived hierarchically porous carbon with nitrogen functionality would have a significant probability as an electrical double-layer capacitor electrode material for the high-performance supercapacitor applications.

Transparent Supercapacitor Display with Redox-Active Metallo-Supramolecular Polymer Films.

The use of metallo-supramolecular polymer (MSP) as a thin-film-based redox supercapacitor electrode material is reported for the first time. Fe(II)- and Ru(II)-based MSPs (polyFe and polyRu, respectively) were synthesized by complexation of appropriate metal salts with 4',4″-(1,4-phenylene)bis-2,2':6',2″-terpyridine, and thin films of these polymers were prepared by spray coating onto an indium tin oxide glass substrate. A study of the energy storage performances of the polyFe and polyRu films in a nonaqueous electrolyte system revealed volumetric capacitances of ∼62.6 ± 3 F/cm3 for polyFe and 98.5 ± 7 F/cm3 for polyRu at a current density of 2 A/cm3. To improve the energy storage performance over a wider potential range, asymmetric supercapacitor (ASC) displays were fabricated with suitable combinations of the MSPs as cathodic materials and Prussian blue as the anodic counter material in a sandwich configuration with a transparent polymeric ion gel as the electrolyte. The fabricated ASCs showed a maximum volumetric energy density (∼10-18 mW h/cm3) that was higher than that of lithium thin-film batteries and a power density (7 W/cm3) comparable to that of conventional electrolyte capacitors, with superb cyclic stability for 10 000 cycles. To demonstrate the practical use of the MSP, the illumination of a light-emitting diode bulb was powered by a laboratory-made device. This work should inspire the development of high-performance thin-film flexible supercapacitors based on MSPs as active cathodic materials.

Nanoarchitectonics of Nanoporous Carbon Materials in Supercapacitors Applications.

High surface area and large pore volume carbon materials having hierarchical nanoporous structure are required in high performance supercapacitors. Such nanoporous carbon materials can be fabricated from organic precursors with high carbon content, such as synthetic biomass or agricultural wastes containing cellulose, hemicellulose, and lignin. Using recently developed unique concept of materials nanoarchitectonics, high performance porous carbons with controllable surface area, pore size distribution, and hierarchy in nanoporous structure can be fabricated. In this review, we will overview the recent trends and advancements on the synthetic methods for the production of hierarchical porous carbons with one- to three-dimensional network structure with superior performance in supercapacitors applications. We highlight the promising scope of accessing nanoporous graphitic carbon materials from: (i) direct conversion of single crystalline self-assembled fullerene nanomaterials and metal organic frameworks, (ii) hard- and soft-templating routes, and (iii) the direct carbonization and/or activation of biomass or agricultural wastes as non-templating routes. We discuss the appealing points of the different synthetic carbon sources and natural precursor raw-materials derived nanoporous carbon materials in supercapacitors applications.

Vortex-Aligned Ordered Film of Crystalline Fullerene C70 Microtubes with Enhanced Photoluminescence and Photovoltaics Properties.

Crystalline fullerene C70 microtubes (FMTs) were produced employing ultrasound-assisted liquid- liquid interfacial precipitation (ULLIP) technique at the interface between fullerene C70 solution in 1,2 dichlorobenzene (DCB) and isopropanol (IPA) at 15 °C. Using the vortex-flow motion of the subphase water (also called Vortex-Langmuir-Blodgett technique), the FMTs were aligned and homogeneous films were prepared at the air-water interface. The aligned FMTs film exhibited enhanced photoluminescence (PL) with PL intensity ~5 times higher than that of the pristine C70. Moreover, the aligned FMT film showed better photovoltaics properties compared with randomly oriented FMTs and pristine C70 film obtained from the spin coating. The compact, directional orientation and proper surface coverage of the FMT film enhanced the charge transport properties in the photovoltaic device.

Nanoporous Carbon Materials Derived from Washnut Seed with Enhanced Supercapacitance.

Nanoporous activated carbons-derived from agro-waste have been useful as suitable and scalable low-cost electrode materials in supercapacitors applications because of their better surface area and porosity compared to the commercial activated carbons. In this paper, the production of nanoporous carbons by zinc chloride activation of Washnut seed at different temperatures (400-1000 °C) and their electrochemical supercapacitance performances in aqueous electrolyte (1 M H2SO4) are reported. The prepared nanoporous carbon materials exhibit hierarchical micro- and meso-pore architectures. The surface area and porosity increase with the carbonization temperature and achieved the highest values at 800 °C. The surface area was found in the range of 922-1309 m2 g-1. Similarly, pore volume was found in the range of 0.577-0.789 cm3 g-1. The optimal sample obtained at 800 °C showed excellent electrochemical energy storage supercapacitance performance. Specific capacitance of the electrode was calculated 225.1 F g-1 at a low current density of 1 A g-1. An observed 69.6% capacitance retention at 20 A g-1 indicates a high-rate capability of the electrode materials. The cycling stability test up to 10,000 cycles revealed the outstanding stability of 98%. The fascinating surface textural properties with outstanding electrochemical performance reveal that Washnut seed would be a feasible agro-waste precursor to prepare nanoporous carbon materials as a low-cost and scalable supercapacitor electrode.

Nanoarchitectonics of Lotus Seed Derived Nanoporous Carbon Materials for Supercapacitor Applications.

Of the available environmentally friendly energy storage devices, supercapacitors are the most promising because of their high energy density, ultra-fast charging-discharging rate, outstanding cycle life, cost-effectiveness, and safety. In this work, nanoporous carbon materials were prepared by applying zinc chloride activation of lotus seed powder from 600 °C to 1000 °C and the electrochemical energy storage (supercapacitance) of the resulting materials in aqueous electrolyte (1M H2SO4) are reported. Lotus seed-derived activated carbon materials display hierarchically porous structures comprised of micropore and mesopore architectures, and exhibited excellent supercapacitance performances. The specific surface areas and pore volumes were found in the ranges 1103.0-1316.7 m2 g-1 and 0.741-0.887 cm3 g-1, respectively. The specific capacitance of the optimum sample was ca. 317.5 F g-1 at 5 mV s-1 and 272.9 F g-1 at 1 A g-1 accompanied by high capacitance retention of 70.49% at a high potential sweep rate of 500 mV s-1. The electrode also showed good rate capability of 52.1% upon increasing current density from 1 to 50 A g-1 with exceptional cyclic stability of 99.2% after 10,000 cycles demonstrating the excellent prospects for agricultural waste stuffs, such as lotus seed, in the production of the high performance porous carbon materials required for supercapacitor applications.

High Surface Area Nanoporous Graphitic Carbon Materials Derived from Lapsi Seed with Enhanced Supercapacitance.

Nanoporous activated carbon materials derived from agro-wastes could be suitable low-cost electrode materials for high-rate performance electrochemical supercapacitors. Here we report high surface area nanoporous carbon materials derived from Lapsi seed agro-waste prepared by zinc chloride (ZnCl2) activation at 700 °C. Powder X-ray diffraction (pXRD) and Raman scattering confirmed the amorphous structure of the resulting carboniferous materials, which also incorporate oxygen-containing functional groups as confirmed by Fourier transform infrared (FTIR) spectroscopy. Scanning and transmission electron microscopy (SEM and TEM) analyses revealed the granular, nanoporous structures of the materials. High-resolution TEM (HR-TEM) confirmed a graphitic carbon structure containing interconnected mesopores. Surface areas and pore volumes of the materials were found, respectively, in the ranges from 931 to 2272 m2 g-1 and 0.998 to 2.845 cm3 g-1, and are thus superior to commercially available activated carbons. High surface areas, large pore volumes and interconnected mesopore structures of these Lapsi seed-derived nanoporous carbon materials lead to their excellent electrochemical supercapacitance performance in aqueous electrolyte (1 M H2SO4) with a maximum specific capacitance of 284 F g-1 at a current density of 1 A g-1. Furthermore, the electrodes showed high-rate capability sustaining 67.7% capacity retention even at high current density of 20 A g-1 with excellent cycle stability achieving 99% capacitance retention even after 10,000 charge-discharge cycles demonstrating the potential of Lapsi seed derived nanoporous carbons as suitable electrode materials in high-performance supercapacitor devices.

Manipulating the Structural Transformation of Fullerene Microtubes to Fullerene Microhorns Having Microscopic Recognition Properties.

We report the production of fullerene microtubes (FMTs), having solid cores bisecting their tubular cavities, from solutions of mixtures of fullerene C60 and C70 and have demonstrated the structural transformation of FMTs to fullerene microhorns (FMHs) upon their exposure to alcohol/mesitylene mixtures at 25 °C. The conically shaped microhorns have hollow interiors and exhibit preferential recognition of silica particles over fullerene C70, polystyrene (PS) latex, PS hydroxylate, or PS carboxylate particles of similar dimensions due to strong electrostatic interactions between negatively charged FMHs and positively charged silica particles.

Hydrous ferric oxide nanoparticles hosted porous polyethersulfone adsorptive membrane: chromium (VI) adsorptive studies and its applicability for water/wastewater treatment.

In this present study, adsorptive membranes for Cr(VI) ion removal were prepared by blending polyethersulfone (PES) with hydrous ferric oxide (HFO) nanoparticles (NPs). The effects of HFO NPs to PES weight ratio (0-1.5) on the physicochemical properties of the resultant HFO/PES adsorptive membranes were investigated with respect to the surface chemistry and roughness as well as structural morphologies using different analytical instruments. The adsorptive performance of the HFO NPs/PES membranes was studied via batch adsorption experiments under various conditions by varying solution pH, initial concentration of Cr(VI), and contact time. The results showed that the membrane made of HFO/PES at a weight ratio of 1.0 exhibited the highest adsorption capacity which is 13.5 mg/g. Isotherm and kinetic studies revealed that the mechanism is best fitted to the Langmuir model and pseudo-second-order model. For filtration of Cr(VI), the best promising membranes showed improved water flux (629.3 L/m2 h) with Cr(VI) ion removal of 75%. More importantly, the newly developed membrane maintained the Cr(VI) concentration below the maximum contamination level (MCL) for up to 9 h.

Supramolecular Aggregates of Tetraphenylethene-Cored AIEgen toward Mechanoluminescent and Electroluminescent Devices.

Luminescent materials possessing both the mechanoluminescence (MCL) and electroluminescence (EL) properties are the quest for sensing and optoelectronic applications. We report on the synthesis of a new tailor-made luminogen, 1,2-bis(4-(1-([1,1'-biphenyl]-4-yl)-2,2-diphenylvinyl)phenyl)-1,2-diphenylethene (TPE 5), using Suzuki coupling reaction with high yield. An aggregation-induced emission (AIE) active complex TPE 5 forms supramolecular spherical aggregates at the air-water interface of a Langmuir trough. As a consequence, a large enhancement of luminescence is obtained from the mono- and multilayer Langmuir-Blodgett films of TPE 5 owing to the AIE effect. The luminogen TPE 5 exhibits a reversible MCL response, displaying photoluminescence switching due to change in the crystalline states under external stimuli. The unique feature of luminescence enhancement upon aggregate formation is utilized for the fabrication of light-emitting diodes with low threshold voltage using supramolecular aggregates as the active layer. This work demonstrates an efficient strategy for obtaining controlled supramolecular aggregates of AIEgen with a potential in the dual applications of MCL and EL.