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.
Graphene electronic devices can be made by top-down (TD) or bottom-up (BU) approaches. This Perspective defines and explains those two approaches and discusses the advantages and limitations of each, ...particularly in the context of graphene fabrication. It is further exemplified using graphene nanoribbons as the prototypical graphene structure that can be prepared using either a TD or BU approach. The TD approach is well-suited for placement of large arrays of devices on a chip using standard patterning tools. However, the TD approach severely compromises the edges of the graphene since present fabrication tools are coarse relative to the ∼0.1 nm definition of a C–C bond. The BU approach can afford exquisite control of the graphene edges; however, placing the structures, en mass, in the locations of interest is often impossible. Also, using the BU approach, it can be very difficult to make device structures long enough for integration with TD-derived probe electrodes. Specific examples are shown, along with an outlook for optimization of future graphene devices in order to capitalize upon the advantages of both TD and BU fabrication methodologies.
Graphene at Fifteen Ye, Ruquan; Tour, James M
ACS nano,
10/2019, Letnik:
13, Številka:
10
Journal Article
Recenzirano
Graphene is a two-dimensional nanomaterial composed of 1–10 layers of carbon atoms in a honeycomb lattice. It has been 15 years since the first isolation of few-layer graphene from graphite by the ...Scotch Tape method. Worldwide research efforts on graphene have been rewarded with enormous breakthroughs in fundamental science and innovative applications. To achieve an influential impact on society, graphene must be manufactured at large scales, be superior to existing products, and be safe to use. In this Perspective, we highlight relevant issues in the quest for commercialization of graphene-containing products. We showcase achievements in improving graphene synthesis while also discussing concerns regarding graphene standardization and graphene’s impact on the environment and human health.
A mixed‐phased Co‐based catalyst composed of Co phosphide and Co phosphate is successfully fabricated for bifunctional water electrolysis. The highly porous morphology in this anodized film enables ...efficient catalytic activity toward water splitting in an extremely low loading mass. The mixed phases in the porous film afford an ability to generate both H2 and O2 in a single electrolyzer.
We present here a straightforward synthesis of highly efficient bifunctional OER/ORR catalysts through a facile laser-induced graphene (LIG) process to produce Co3O4/LIG. The Co3O4/LIG showed OER and ...ORR activity comparable to noble metal-based catalysts in alkaline electrolyte. Furthermore, the Co3O4/LIG exhibited promising performance in Zn-air and Li-O2 batteries. The rechargeable Zn-air battery has an open-circuit potential of 1.46 V and a high power density of 84.2 mW/cm2 at 100 mA/cm2. The Li-O2 battery with the Co3O4/LIG cathode exhibits low overpotentials in both charge and discharge processes and excellent cycling stability up to 242 cycles.
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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.
Wood as a renewable naturally occurring resource has been the focus of much research and commercial interests in applications ranging from building construction to chemicals production. Here, a ...facile approach is reported to transform wood into hierarchical porous graphene using CO2 laser scribing. Studies reveal that the crosslinked lignocellulose structure inherent in wood with higher lignin content is more favorable for the generation of high‐quality graphene than wood with lower lignin content. Because of its high electrical conductivity (≈10 Ω per square), graphene patterned on wood surfaces can be readily fabricated into various high‐performance devices, such as hydrogen evolution and oxygen evolution electrodes for overall water splitting with high reaction rates at low overpotentials, and supercapacitors for energy storage with high capacitance. The versatility of this technique in formation of multifunctional wood hybrids can inspire both research and industrial interest in the development of wood‐derived graphene materials and their nanodevices.
Laser‐induced porous graphene (LIG) is formed on wood by laser irradiation. This LIG is engineered into energy‐storage devices and electrocatalysis electrodes. The LIG from pine (P‐LIG) is coated with polyaniline to form supercapacitors and with metals Co, Ni, and Fe to form electrocatalysts. The electrocatalysis of water using metal‐coated P‐LIG produces H2 and O2.
The existing structural models of graphene oxide (GO) contradict each other and cannot adequately explain the acidity of its aqueous solutions. Inadequate understanding of chemical structure can lead ...to a misinterpretation of observed experimental phenomena. Understanding the chemistry and structure of GO should enable new functionalization protocols while explaining GO’s limitations due to its water instability. Here we propose an unconventional view of GO chemistry and develop the corresponding “dynamic structural model” (DSM). In contrast to previously proposed models, the DSM considers GO as a system, constantly changing its chemical structure due to interaction with water. Using potentiometric titration, 13C NMR, FTIR, UV–vis, X-ray photoelectron microscopy, thermogravimetric analysis, and scanning electron microscopy we show that GO does not contain any significant quantity of preexisting acidic functional groups, but gradually generates them through interaction with water. The reaction with water results in C–C bond cleavage, formation of vinylogous carboxylic acids, and the generation of protons. An electrical double layer formed at the GO interface in aqueous solutions plays an important role in the observed GO chemistry. Prolonged exposure to water gradually degrades GO flakes converting them into humic acid-like structures. The proposed DSM provides an explanation for the acidity of GO aqueous solutions and accounts for most of the known spectroscopic and experimental data.
As a two-dimensional (2D) sp2-bonded carbon allotrope, graphene has attracted enormous interest over the past decade due to its unique properties, such as ultrahigh electron mobility, uniform ...broadband optical absorption and high tensile strength. In the initial research, graphene was isolated from natural graphite, and limited to small sizes and low yields. Recently developed chemical vapor deposition (CVD) techniques have emerged as an important method for the scalable production of large-size and high-quality graphene for various applications. However, CVD-derived graphene is polycrystalline and demonstrates degraded properties induced by grain boundaries. Thus, the next critical step of graphene growth relies on the synthesis of large graphene single crystals. In this Account, we first discuss graphene grain boundaries and their influence on graphene’s properties. Mechanical and electrical behaviors of CVD-derived polycrystalline graphene are greatly reduced when compared to that of exfoliated graphene. We then review four representative pathways of pretreating Cu substrates to make millimeter-sized monolayer graphene grains: electrochemical polishing and high-pressure annealing of Cu substrate, adding of additional Cu enclosures, melting and resolidfying Cu substrates, and oxygen-rich Cu substrates. Due to these pretreatments, the nucleation site density on Cu substrates is greatly reduced, resulting in hexagonal-shaped graphene grains that show increased grain domain size and comparable electrical properties as to exfoliated graphene. Also, the properties of graphene can be engineered by its shape, thickness and spatial structure. Thus, we further discuss recently developed methods of making graphene grains with special spatial structures, including snowflakes, six-lobed flowers, pyramids and hexagonal graphene onion rings. The fundamental growth mechanism and practical applications of these well-shaped graphene structures should be interesting topics and deserves more attention in the near future. Following that, recent efforts in fabricating large single-crystal monolayer graphene on other metal substrates, including Ni, Pt, and Ru, are also described. The differences in growth conditions reveal different growth mechanisms on these metals. Another key challenge for graphene growth is to make graphene single crystals on insulating substrates, such as h-BN, SiO2, and ceramic. The recently developed plasma-enhanced CVD method can be used to directly synthesize graphene single crystals on h-BN substrates and is described in this Account as well. To summarize, recent research in synthesizing millimeter-sized monolayer graphene grains with different pretreatments, graphene grain shapes, metal catalysts, and substrates is reviewed. Although great advancements have been achieved in CVD synthesis of graphene single crystals, potential challenges still exist, such as the growth of wafer-sized graphene single crystals to further facilitate the fabrication of graphene-based devices, as well as a deeper understanding of graphene growth mechanisms and growth dynamics in order to make graphene grains with precisely controlled thicknesses and spatial structures.
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