Laser‐induced graphene (LIG) is a 3D porous material prepared by direct laser writing with a CO2 laser on carbon materials in ambient atmosphere. This technique combines 3D graphene preparation and ...patterning into a single step without the need for wet chemical steps. Since its discovery in 2014, LIG has attracted broad research interest, with several papers being published per month using this approach. These serve to delineate the mechanism of the LIG‐forming process and to showcase the translation into many application areas. Herein, the strategies that have been developed to synthesize LIG are summarized, including the control of LIG properties such as porosity, composition, and surface characteristics, and the advancement in methodology to convert diverse carbon precursors into LIG. Taking advantage of the LIG properties, the applications of LIG in broad fields, such as microfluidics, sensors, and electrocatalysts, are highlighted. Finally, future development in biodegradable and biocompatible materials is briefly discussed.
Laser‐induced graphene is a 3D porous graphene material synthesized by laser irradiation on commercial polymers or natural materials using a CO2 infrared laser under ambient conditions. This method presents advantages over the traditional 3D graphene synthesis. Recent progress in synthesis and application, and perspectives for future opportunities are highlighted.
Laser-Induced Graphene Ye, Ruquan; James, Dustin K; Tour, James M
Accounts of chemical research,
07/2018, Letnik:
51, Številka:
7
Journal Article
Recenzirano
Conspectus Research on graphene abounds, from fundamental science to device applications. In pursuit of complementary morphologies, formation of graphene foams is often preferred over the native ...two-dimensional (2D) forms due to the higher available area. Graphene foams have been successfully prepared by several routes including chemical vapor deposition (CVD) methods and by wet-chemical approaches. For these methods, one often needs either high temperature furnaces and highly pure gases or large amounts of strong acids and oxidants. In 2014, using a commercial laser scribing system as found in most machine shops, a direct lasing of polyimide (PI) plastic films in the air converted the PI into 3D porous graphene, a material termed laser-induced graphene (LIG). This is a one-step method without the need for high-temperature reaction conditions, solvent, or subsequent treatments, and it affords graphene with many five-and seven-membered rings. With such an atomic arrangement, one might call LIG “kinetic graphene” since there is no annealing in the process that causes the rearrangement to the preferred all-six-membered-ring form. In this Account, we will first introduce the approaches that have been developed for making LIG and to control the morphology as either porous sheets or fibrils, and to control porosity, composition, and surface properties. The surfaces can be varied from being either superhydrophilic with a 0° contact angle with water to being superhydrophobic having >150° contact angle with water. While it was initially thought that the LIG process could only be performed on PI, it was later shown that a host of other polymeric substrates, nonpolymers, metal/plastic composites, and biodegradable and naturally occurring materials and foods could be used as platforms for generating LIG. Methods of preparation include roll-to-roll production for fabrication of in-plane electronics and two different 3D printing (additive manufacturing) routes to specific shapes of LIG monoliths using both laminated object manufacturing and powder bed fabrication methods. Use of the LIG in devices is performed very simply. This is showcased with high performance supercapacitors, fuel cell materials for oxygen reduction reactions, water splitting for both hydrogen and oxygen evolution reactions coming from the same plastic sheet, sensor devices, oil/water purification platforms, and finally applications in both passive and active biofilm inhibitors. So the ease of formation of LIG, its simple scale-up, and its utility for a range of applications highlights the easy transition of this substrate-bound graphene foam into commercial device platforms.
Recent research has focused upon the growth of the graphene, with a concentration on the synthesis of graphene and related materials using both solution processes and high temperature chemical vapor ...and solid growth methods. Protocols to prepare high aspect ratio graphene nanoribbons from multi‐walled carbon nanotubes have been developed as well as techniques to grow high quality graphene for electronics and other applications where high quality is needed. Graphene materials have been manipulated and modified for use in applications such as transparent electrodes, field effect transistors, thin film transistors and energy storage devices. This review summarizes the development of graphene and related materials.
Recent research has focused on graphene materials such as graphene nanoribbons (left) and pristine graphene oxide (right). Synthetic protocols for producing graphene materials are rapidly advancing, with applications in transparent conductive membranes, fibers and coatings, oil field fluids and many other commercially viable uses. This review is a summary of graphene materials endeavors.
Graphene Chemistry: Synthesis and Manipulation Sun, Zhengzong; James, Dustin K; Tour, James M
The journal of physical chemistry letters,
10/2011, Letnik:
2, Številka:
19
Journal Article
Recenzirano
Monolayer graphene is a two-dimensional material with fascinating electrical and optical properties that has brought great possibilities and challenges to chemists. The possibilities include the many ...applications in which graphene could be exploited, and the challenges involve optimizing synthetic strategies and manipulating the structure and properties so that graphene can be used in those applications. Here, we cover a portion of the recent progress toward using chemical techniques to render graphene available for incorporation into electronic and optical devices. With top-down and bottom-up strategies, the geometry and thickness of graphene have been well-tuned. The methods for producing structure-doped materials, such as nitrogen doping and h-BNC hybrid structures, are discussed along with the properties of those doped materials. Finally, covalent functionalization of graphene’s surfaces and edges, such as hydrogenation and the diazonium and azide reactions, will be discussed as they have become powerful tools to modify the properties of graphene.
Graphene’s unique physical and electrical properties (high tensile strength, Young’s modulus, electron mobility, and thermal conductivity) have led to its nickname of “super carbon.” Graphene ...research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp2 carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar fibers and in the fabrication of large area transparent electrodes. Using solid carbon sources such as polymers, food, insects, and waste, we can grow monolayer and bilayer graphene directly on metal catalysts, and carbon-sources containing nitrogen can produce nitrogen-doped graphene. The resulting graphene can be transferred to other surfaces, such as metal grids, for potential use in transparent touch screens for applications in personal electronics and large area photovoltaic devices. Because the transfer of graphene from one surface to another can lead to defects, low yields, and higher costs, we have developed methods for growing graphene directly on the substrates of interest. We can also produce patterned graphene to make GNRs or graphane/graphene superlattices within a single sheet. These superlattices could have multiple functions for use in sensors and other devices. This Account only touches upon this burgeoning area of materials chemistry, and the field will continue to expand as researchers imagine new forms and applications of graphene.
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Nanotechnology and nanomaterials have attracted interest due to their potential in mitigating contemporary environmental challenges, such as the stressors imposed by increased ...industrial and agricultural activities, and the deterioration of air, soil and water quality. In particular, advanced technologies that harness carbon-based nanomaterials are poised to emerge as tools that provide new solutions for the global water crises. These tools include, electrically conductive membrane processes, which uniquely combine a separation process with a functional surface. In this respect, laser-induced graphene (LIG) and carbon nanotubes (CNTs) are electrically conductive carbon nanomaterials that hold great utility in a multitude of environmental applications, including the development of fouling-resistant systems for desalination and water treatment, enhanced separation methods, and innovative pollutant sensing and electrocatalytic platforms. Consequently, this review article describes and compares some important recent advances in LIG- and CNT-based electroactive surfaces. The discussion of LIG as an emerging carbon material set in context with CNTs is intended to shed light on future directions and development possibilities to meet the growing global challenges in terms of water treatment applications of both materials as well as other electrically conductive carbon-based nanomaterials exhibiting exceptional performance and versatility.
Graphene, graphene oxide (GO), and graphene nanoribbons (GNRs) are important materials that are related through their carbon‐based planar structures and attractive physical properties. Many ...applications have been proposed for these materials, such as composites, touch‐screen displays, and electronic devices. Based on research done in the Tour laboratory, we offer a tutorial on the solution phase chemical synthesis of GNRs through two routes. The first route involves the oxidation of multi‐walled carbon nanotubes (MWCNTs) to produce GO nanoribbons that contain oxidized functionality and that can be reduced to GNRs. The second route to GNRs involves the splitting of MWCNTs by intercalation of potassium metal at elevated temperature. The routes are complementary and produce materials that can be used in diverse applications.
Review: Graphene nanoribbons (GNRs) can be produced using a variety of chemical methods. The solution‐based chemical synthesis of GNRs through oxidation or reduction of multi‐walled carbon nanotubes using protocols developed in the Tour group is reviewed, giving the reader an overview that benefits from the hindsight of several years of research in the group.
Alzheimer's disease and other related neurodegenerative disorders known as tauopathies are characterized by the accumulation of abnormally phosphorylated and aggregated forms of the ...microtubule-associated protein tau. Several laboratories have identified a 17 kD proteolytic fragment of tau in degenerating neurons and in numerous cell culture models that is generated by calpain cleavage and speculated to contribute to tau toxicity. In the current study, we employed a Drosophila tauopathy model to investigate the importance of calpain-mediated tau proteolysis in contributing to tau neurotoxicity in an animal model of human neurodegenerative disease. We found that mutations that disrupted endogenous calpainA or calpainB activity in transgenic flies suppressed tau toxicity. Expression of a calpain-resistant form of tau in Drosophila revealed that mutating the putative calpain cleavage sites that produce the 17 kD fragment was sufficient to abrogate tau toxicity in vivo. Furthermore, we found significant toxicity in the fly retina associated with expression of only the 17 kD tau fragment. Collectively, our data implicate calpain-mediated proteolysis of tau as an important pathway mediating tau neurotoxicity in vivo.
This paper reviews the various methods used to measure the electrical characteristics of individual or small groups of molecules, including crossed-wire junctions, mechanically controllable break ...junctions, conducting atomic force microscopy, scanning tunneling microscopy, molecular electronics on silicon surfaces, the NanoCell, nanopores, and other devices. It is shown that in the most common embodiment, the metal−molecule−metal junction, the assembly must be considered in whole. The characteristics of the molecule cannot be easily separated from the metal electrodes connected to it or from the method used to do the testing. I(V,T) data is necessary to rule out non-molecular transport mechanisms such as metal filament formation.
Microparticles are produced by various cells due to a number of different stimuli in the circulatory system. Shear stress has been shown to injure red blood cells resulting in hemolysis or ...non-reversible sub-hemolytic damage. We hypothesized that, in the sub-hemolytic shear range, there exist sufficient mechanical stimuli for red blood cells to respond with production of microparticles. Red blood cells isolated from blood of healthy volunteers were exposed to high shear stress in a microfluidic channel to mimic mechanical trauma similar to that occurring in ventricular assist devices. Utilizing flow cytometry techniques, both an increase of shear rate and exposure time showed higher concentrations of red blood cell microparticles. Controlled shear rate exposure shows that red blood cell microparticle concentration may be indicative of sub-hemolytic damage to red blood cells. In addition, properties of these red blood cell microparticles produced by shear suggest that mechanical trauma may underlie some complications for cardiovascular patients.
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