A simple and facile method for obtaining patterned graphene under ambient conditions on the surface of diverse materials ranging from renewable precursors such as food, cloth, paper, and cardboard to high-performance polymers like Kevlar or even on natural coal would be highly desirable. Here, we report a method of using multiple pulsed-laser scribing to convert a wide range of substrates into laser-induced graphene (LIG). With the increased versatility of the multiple lase process, highly conductive patterns can be achieved on the surface of a diverse number of substrates in ambient atmosphere. The use of a defocus method results in multiple lases in a single pass of the laser, further simplifying the procedure. This method can be implemented without increasing processing times when compared with laser induction of graphene on polyimide (Kapton) substrates as previously reported. In fact, any carbon precursor that can be converted into amorphous carbon can be converted into graphene using this multiple l...

Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food

The complex structure of wood, one of the most abundant biomaterials on Earth, has been optimized over 270 million years of tree evolution. This optimization has led to the highly efficient water and nutrient transport, mechanical stability and durability of wood. The unique material structure and pronounced anisotropy of wood endows it with an array of remarkable properties, yielding opportunities for the design of functional materials. In this Review, we provide a materials and structural perspective on how wood can be redesigned via structural engineering, chemical and/or thermal modification to alter its mechanical, fluidic, ionic, optical and thermal properties. These modifications enable a diverse range of applications, including the development of high-performance structural materials, energy storage and conversion, environmental remediation, nanoionics, nanofluidics, and light and thermal management. We also highlight advanced characterization and computational-simulation approaches for understanding the structure–property–function relationships of natural and modified wood, as well as informing bio-inspired synthetic designs. In addition, we provide our perspective on the future directions of wood research and the challenges and opportunities for industrialization. The porous hierarchical structure and anisotropy of wood make it a strong candidate for the design of materials with various functions, including load bearing, multiscale mass transport, and optical and thermal management. In this Review, the composition, structure, characterization methods, modification strategies, properties and applications of natural and modified wood are discussed.

Structure-property-function relationships of natural and engineered wood

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: From Discovery to Translation.

J.Y. and W.L.Z. contributed equally to this work. The research reported in this publication was supported by the King Abdullah University of Science and Technology – King Abdulaziz University (KAUST–KAU) Initiative (Grant # OSR-2018 KAUST-KAU-3903).

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Synthesis Strategies of Porous Carbon for Supercapacitor Applications

ConspectusResearch 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 grap...

Laser-Induced Graphene

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 Graphene Formation on Wood.

Laser-induced graphene (LIG) has received much attention since it enables simple and rapid synthesis of porous graphene. This work presents a robust direct-write LIG-based gas sensor, which senses gases based on thermal conductivity, similar to a katharometer sensor. The gas sensors are fabricated by lasing polyimide substrates with a 10.6 μm CO2 laser to synthesize LIG. This enables the formation of flexible gas sensors which could be incorporated on a variety of surfaces. High surface area and thermal conductivity of the LIG results in rapid response times for all studied gases. The gas sensors are also embedded in cement to form a refractory composite material. These sensors are used to determine composition of various gas mixtures, such as N2 and CO2, which are the most abundant gaseous species in flue gas. Thus, LIG based embeddable sensors could be incorporated in composites to enable electronically functional construction materials.

Laser-Induced Graphene for Flexible and Embeddable Gas Sensors

Triboelectric nanogenerators (TENGs) show exceptional promise for converting wasted mechanical energy into electrical energy. This study investigates the use of laser-induced graphene (LIG) composites as an exciting class of triboelectric materials in TENGs. Infrared laser irradiation is used to convert the surfaces of the two carbon sources, polyimide (PI) and cork, into LIG. This gives the bilayer composite films the high conductivity associated with LIG and the triboelectric properties of the carbon source. A LIG/PI composite is used to fabricate TENGs based on conductor-to-dielectric and metal-free dielectric-to-dielectric device geometries with open-circuit voltages >3.5 kV and peak power >8 mW. Additionally, a single sheet of PI is converted to a metal-free foldable TENG. The LIG is also embedded within a PDMS matrix to form a single-electrode LIG/PDMS composite TENG. This single-electrode TENG is highly flexible and stretchable and was used to generate power from mechanical contact with skin. The LIG composites present a class of triboelectric materials that can be made from naturally occurring and synthetic carbon sources.

Laser-Induced Graphene Triboelectric Nanogenerators.

The hybridization of graphene with other inorganic nanostructures has endowed graphene with enhanced and varied functionalities. Here we demonstrate a facile and improved approach to convert biodegradable cedar wood into graphene embedded with various metal nanocrystals (cedar-LIG-M, LIG is laser-induced graphene, M = Cu, Co, Ni, Fe, NiFe) by sonication-assisted soaking and one-step CO2 laser scribing. Organic biomass was transformed to hierarchical porous graphene via laser induction, whereas metal salts were reduced to elemental metals simultaneously by the carbothermal reaction and reducing atmosphere generated during the lignocellulose decomposition. The as-prepared cedar-LIG-M possesses an ordered porous structure, good conductivity, unique ferromagnetic behavior and excellent electrochemical catalytic performance. As a demonstration, the cedar-LIG-NiFe electrode has a low overpotential of 296 mV at a current density of 10 mA cm–2 for oxygen evolution reactions. The performance of the electrode conti...

Yieu Chyan

Papers

Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food

Laser-Induced Graphene Formation on Wood.

Laser-Induced Graphene for Flexible and Embeddable Gas Sensors

Laser-Induced Graphene Triboelectric Nanogenerators.

Laser-Induced Graphene from Wood Impregnated with Metal Salts and Use in Electrocatalysis