Optically Transparent Carbon Nanotube Film Electrode for Thin Layer Spectroelectrochemistry

Bidimensional Spectroelectrochemistry with Tunable Thin-Layer Thickness

Bidimensional spectroelectrochemistry (Bidim-SEC) is an instrumental technique that provides operando UV/vis absorption information on electrochemical processes from two different points of view, using concomitantly a parallel and a normal optical configuration. The parallel configuration provides information about chemical species present in the diffusion layer, meanwhile the normal arrangement supplies information about changes occurring both in the diffusion layer and, mainly, on the electrode surface. The choice of a suitable cell to perform Bidim-SEC experiments is critical, especially while working under a thin-layer regime. So far, most of the proposed Bidim-SEC cells rely on the use of spacers to define the thin-layer thickness, which leads to working with constant thickness values. Herein, we propose a novel Bidim-SEC cell that enables easy-to-use micrometric control of the thin-layer thickness using a piezoelectric positioner. This device can be used for the study of complex interfacial systems and also to easily measure the key parameters of an electrochemical process. As a proof of concept, the study of the roughening of a gold electrode in KCl medium is performed, identifying key steps in the passivation and nanoparticle generation on the gold surface.

Electrochemical Long Period Fiber Grating Sensing for Electroactive Species

We present an electrochemical long period fiber grating (LPFG) sensor for electroactive species with an optically transparent electrode. The sensor was fabricated by coating indium tin oxide onto the surface of LPFG using a polygonal barrel-sputtering method. LPFG was produced by an electric arc-induced technique. The sensing is based on change in the detection of electron density on the electrode surface during potential application and its reduction by electrochemical redox of analytes. Four typical electroactive species of methylene blue, hexaammineruthenium(III), ferrocyanide, and ferrocenedimethanol were used to investigate the sensor performance. The concentrations of analytes were determined by the modulation of the potential as the change in transmittance around the resonance band of LPFG. The sensitivity of the sensor, particularly to methylene blue, was high, and the sensor responded to a wide concentration range of 0.001 mM to 1 mM.

A Review on Flexible and Transparent Energy Storage System

Due to the broad application prospect, flexible and transparent electronic device has been widely used in portable wearable devices, energy storage smart window and other fields, which owns many advantages such as portable, foldable, small-quality, low-cost, good transparency, high performance and so on. All these electronic devices are inseparable from the support of energy storage device. Energy storage device, like lithium-ion battery and super capacitor, also require strict flexibility and transparency as the energy supply equipment of electronic devices. Here, we demonstrate the development and applications of flexible and transparent lithium-ion battery and super capacitor. In particular, carbon nanomaterials are widely used in flexible and transparent electronic device, due to their excellent optical and electrical properties and good mechanical properties. For example, carbon nanotubes with high electrical conductivity and low density have been widely reported by researchers. Otherwise, graphene as an emerging two-dimensional material with electrical conductivity and carrier mobility attracts comparatively more attention than that of other carbon nanomaterials. Substantial effort has been put on the research for graphene-based energy storage system by researchers from all over the world. But, there is still a long way to accomplish this goal of improving the performance for stretchable and transparent electronic device due to the existing technical conditions.

Recent advances in spectroelectrochemistry

The integration of two quite different techniques, conventional electrochemistry and spectroscopy, into spectroelectrochemistry (SEC) provides a complete description of chemically driven electron transfer processes and redox events for different kinds of molecules and nanoparticles. SEC possesses interdisciplinary advantages and can further expand the scopes in the fields of analysis and other applications, emphasizing the hot issues of analytical chemistry, materials science, biophysics, chemical biology, and so on. Considering the past and future development of SEC, a review on the recent progress of SEC is presented and selected examples involving surface-enhanced Raman scattering (SERS), ultraviolet-visible (UV-Vis), near-infrared (NIR), Fourier transform infrared (FTIR), fluorescence, as well as other SEC are summarized to fully demonstrate these techniques. In addition, the optically transparent electrodes and SEC cell design, and the typical applications of SEC in mechanism study, electrochromic device fabrication, sensing and protein study are fully introduced. Finally, the key issues, future perspectives and trends in the development of SEC are also discussed.

Heatable carbon nanotube composite membranes for sustainable recovery from biofouling

Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling. Microfiltration polycarbonate/carbon-nanotubes hybrid membranes were fabricated using drawable nanotubes that maintained the porosity and provided electrical conductivity to the membrane. Less than 25 V potential and 2-3 W power increase membrane temperature to 100°C in ~10 s. This temperature is above what most microbial life, bacteria and viruses can handle. When this membrane was employed, filtered Escherichia coli collected on its surface were successfully annihilated within 1 min. Ohmic heating of this membrane could be an effective solution to combat biofouling and complications associated with membrane-based filtration. This is a novel and highly desirable approach to combat biofouling, due to its simplicity and economic advantage.

Degradation mechanisms of silver nanowire electrodes under ultraviolet irradiation and heat treatment

We report the degradation mechanisms of the silver nanowire (Ag NW) electrodes that play a significantly important role in the stability of wearable and flexible devices. The degradation mechanisms behind the increase in the sheet resistances of Ag NW electrodes were clarified by investigating the variations in the structure and the chemical composition of the Ag NW electrodes caused by ultraviolet irradiation and thermal treatment. While the shapes of the Ag NWs were affected by melting during the thermal degradation process, the chemical composition of the polyvinylpyrrolidone protective layer on the surfaces of the Ag NWs was not changed. Ultraviolet irradiation deformed the shapes of the Ag NWs because nitrogen or oxygen atoms were introduced to the silver atoms on the surfaces of the Ag NWs. A graphene-oxide flake was coated on the Ag NW electrodes by using a simple dipping method to prevent ultraviolet irradiation and ozone contact with the surfaces of the Ag NWs, and the increase in the sheet resistance in the graphene-oxide-treated Ag NWs was suppressed. These observations will be of assistance to researchers trying to find novel ways to improve the stability of the Ag NW electrodes in next-generation wearable devices.

Peptide-Based Ligand for Active Delivery of Liposomal Doxorubicin

Doxorubicin (DOX) has been extensively used in the clinic to treat malignant tumors such as leukemias and Hodgkin’s lymphoma. However, the severe cardiotoxicity associated with the use of DOX requests the development of alternative and efficient pharmaceutical formulations. The PEGylated liposome of DOX can significantly reduce the cardiotoxicity but still lacks the active targeting towards cancer cells. Modification of liposomal DOX with active ligands would then be a rational approach to enhance the transportation of the toxin into tumor cells. Currently used targeting ligands include antibodies, proteins, small molecules, and peptides. By virtue of the advantages such as easy preparation, lower cost, and elevated resistance to enzymatic degradation, peptides are attracting a significant amount of interest as active targeting ligands for pharmaceutics. In this paper, we will briefly discuss the application of peptide ligands for the improvement of the therapeutic efficacy of liposomal DOX.

Quantitative SERS Detection of Trace Glutathione with Internal Reference Embedded Au-core/Ag-shell Nanoparticles

Surface-enhanced Raman scattering (SERS) has been widely studied and applied for over three decades. However, reliable SERS detection of molecules with low polarizability is still suffering from poor sensitivity and reproducibility. In this paper, we have reported a new strategy for performing quantitative SERS detection of Raman insensitive Glutathione (GSH), based on GSH-induced replacement of a highly Raman sensitive four-mercaptopyridine (MP) adsorbed on the surface of four-aminothiophenol (ATP) embedded Au-core/Ag-shell particles. This replacement led to a strong decrease of the MP SERS signal, which was used to determine the concentration of GSH. The adoption of GSH-induced Raman probe replacement leads to high sensitivity, while the use of internal reference method provides an improved accuracy of the GSH quantification.