Lead Selenide Nanostructures Self-Assembled across Multiple Length Scales and Dimensions

A self-assembly approach to lead selenide (PbSe) structures that have organized across multiple length scales and multiple dimensions has been achieved. These structures consist of angstrom-scale 0D PbSe crystals, synthesized via a hot solution process, which have stacked into 1D nanorods via aligned dipoles. These 1D nanorods have arranged into nanoscale 2D sheets via directional short-ranged attraction. The nanoscale 2D sheets then further aligned into larger 2D microscale planes. In this study, the authors have characterized the PbSe structures via normal and cryo-TEM and EDX showing that this multiscale multidimensional self-assembled alignment is not due to drying effects. These PbSe structures hold promise for applications in advanced materials—particularly electronic technologies, where alignment can aid in device performance

Carbon-Based Nanomaterials as Novel Nanosensors [Editorial]

In recent years, nanosensor technology has experienced a rapid development because of the extensive scientific efforts in understanding of nanoscale phenomena and achieving innovative nanofabrication techniques. Carbon-based nanomaterials (CBNs), such as fullerenes, graphene, nanodiamonds, carbon nanotubes, and carbon nanodots, have recently gained considerable attention among scientific communities due to their unique chemical and physical properties. Thanks to intensive research efforts, the CBNs have found their place in a wide range of applications. These CBNs stand out as novel nanosensors due to their supreme performance in detecting heavy metal ions, gas molecules, food additives, antibodies, and toxic pesticides, as well as reporters for bioimaging. This special issue, to be published in 2017, addresses recent progress in the synthesis, characterization, structure-property relationships and applications of CBNs as novel nanosensors. We are confident that the accrual of these contributions will facilitate the applications of CBNs as innovative nanosensors in meeting the urgent needs for environmental monitoring, food safety control, healthcare, homeland security, and so forth. We have selected five papers, representing four different frontiers of this topic: graphene, silver nanoparticles, carbon nanotubes, and carbon nanodots

Synthesis of Co-Electrospun Lead Selenide Nanostructures within Anatase Titania Nanotubes for Advanced Photovoltaics

Inorganic nano-scale heterostructures have many advantages over hybrid organic-inorganic dye-sensitized solar cells (DSSC or Grätzel cells), including their resistance to photo-bleaching, thermal stability, large specific surface areas, and general robustness. This study presents a first-of-its-kind low-cost all-inorganic lead selenide-anatase titania (PbSe/TiO2) nanotube heterostructure material for photovoltaic applications. Herein, PbSe nanostructures have been co-electrospun within a hollow TiO2 nanotube with high connectivity for highly efficient charge carrier flow and electron-hole pair separation. This material has been characterized by transmission electron microscopy (TEM), electron diffraction, energy dispersive X-ray spectroscopy (EDX) to show the morphology and material composition of the synthesized nanocomposite. Photovoltaic characterization has shown this newly synthesized proof-of-concept material can easily produce a photocurrent under solar illumination, and, with further refinement, could reveal a new direction in photovoltaic materials

Multifunctional Carbon Nanostructures for Advanced Energy Storage Applications

Carbon nanostructures—including graphene, fullerenes, etc.—have found applications in a number of areas synergistically with a number of other materials. These multifunctional carbon nanostructures have recently attracted tremendous interest for energy storage applications due to their large aspect ratios, specific surface areas, and electrical conductivity. This succinct review aims to report on the recent advances in energy storage applications involving these multifunctional carbon nanostructures. The advanced design and testing of multifunctional carbon nanostructures for energy storage applications—specifically, electrochemical capacitors, lithium ion batteries, and fuel cells—are emphasized with comprehensive examples

Enhanced Chemical and Electrochemical Stability of Polyaniline-Based Layer-by-Layer Films

Polyaniline (PANI) has been widely used as an electroactive material in various applications including sensors, electrochromic devices, solar cells, electroluminescence, and electrochemical energy storage, owing to PANI’s unique redox properties. However, the chemical and electrochemical stability of PANI-based materials is not sufficiently high to maintain the performance of devices under many practical applications. Herein, we report a route to enhancing the chemical and electrochemical stability of PANI through layer-by-layer (LbL) assembly. PANI was assembled with different types of polyelectrolytes, and a comparative study between three different PANI-based layer-by-layer (LbL) films is presented here. Polyacids of different acidity and molecular structure, i.e., poly(acrylic acid) (PAA), polystyrene sulfonate (PSS), and tannic acid (TA), were used. The effect of polyacids’ acidity on film growth, conductivity, and chemical and electrochemical stability of PANI was investigated. The results showed that the film growth of the LbL system depended on the acidic strength of the polyacids. All LbL films exhibited improved chemical and electrochemical stability compared to PANI films. The doping level of PANI was strongly affected by the type of dopants, resulting in different chemical and electrochemical properties; the strongest polyacid (PSS) can provide the highest conductivity and chemical stability of conductive PANI. However, the electrochemical stability of PANI/PAA was found to be better than all the other films

Detection of Halogenated Organics by Their Inhibitory Action in a Catalytic Reaction Between Dimethyl Acetylenedicarboxylate and 2-methyl-4-nitroaniline

The purpose of this paper is to report on the detection of toxic halogenated organic compounds in water using their inhibitory action on a pyridine-catalyzed reaction between dimethyl acetylenedicarboxylate (DMAD) and 2-methyl-4-nitroaniline (MNA). Previous work has shown that similar techniques can successfully lower the detection limit of sulfides and arsines in water samples, compared to their standard photometric detection methods. This paper highlights the optimization, selectivity, and sensitivity studies of the proposed sensing scheme. Optimization shows that the pyridine-catalyzed reaction is more favorable at 4 mM DMAD and 8 mM MNA. It was also determined that the inhibitory effect of halogenated organic compounds is more pronounced when carried out at 60°C. Using optimized reaction conditions, the limit of quantification for the four regulated trihalomethanes (THMs) was approximately 80 ppm. In addition, the sensing method is selective to THMs and a few other halogenated organics. These promising results demonstrate the further success of this technique for sensitive, selective detection, and future work will be carried out to incorporate the technique in sensing applications for THMs in drinking water

Clean water recycling through adsorption via heterogeneous nanocomposites: Silver-based metal-organic framework embellished with graphene oxide and MXene

Cationic methylene blue (MB) and anionic orange G (OG) dyes were adsorbed using the first-ever synthesized nanocomposite of MXene-AgMOF. At 200 mg/L and 0.01 g, GO-AgMOF, MXene-AgMOF, and AgMOF were able to adsorb 99.9%, 99.0%, and 98.0% of cationic MB dye, respectively, from water. The nanocomposites were characterized both before and after adsorption using different characterization techniques. These nanocomposites show promise as cationic contaminant adsorbents, with an adsorption capacity of 399.9 mg/g for GO-AgMOF. Also, the enhanced adsorption capacity of AgMOF for anionic and cationic dyes suggests its potential use in environmental remediation when combined with MXene

Multifunctional Nanofibers towards Active Biomedical Therapeutics

One-dimensional (1-D) nanostructures have attracted enormous research interest due to their unique physicochemical properties and wide application potential. These 1-D nanofibers are being increasingly applied to biomedical fields owing to their high surface area-to-volume ratio, high porosity, and the ease of tuning their structures, functionalities, and properties. Many biomedical nanofiber reviews have focused on tissue engineering and drug delivery applications but have very rarely discussed their use as wound dressings. However, nanofibers have enormous potential as wound dressings and other clinical applications that could have wide impacts on the treatment of wounds. Herein, the authors review the main fabrication methods of nanofibers as well as requirements, strategies, and recent applications of nanofibers, and provide perspectives of the challenges and opportunities that face multifunctional nanofibers for active therapeutic applications