Facile Synthesis of Mesoporous Nanohybrid Two-Dimensional Layered Ni-Cr-S and Reduced Graphene Oxide for High-Performance Hybrid Supercapacitors.

This study describes the single-step synthesis of a mesoporous layered nickel-chromium-sulfide (NCS) and its hybridization with single-layered graphene oxide (GO) using a facile, inexpensive chemical method. The conductive GO plays a critical role in improving the physicochemical and electrochemical properties of hybridized NCS/reduced GO (NCSG) materials. The optimized mesoporous nanohybrid NCSG is obtained when hybridized with 20% GO, and this material exhibits a very high specific surface area of 685.

Simple fabrication of CoO nanoparticles on N-doped laser-induced graphene for high-performance supercapacitors.

This study demonstrates a simple strategy to fabricate CoO on N-doped laser-induced graphene (CoO-NLIG) based on duplicate laser pyrolysis, enabling the generation of CoO nanoparticles and heteroatom doping in laser-induced graphene (LIG). Morphological analyses reveal the uniform distribution of CoO nanoparticles on the surface of the LIG structure. The modification of NLIG with CoO nanoparticles results in impressive electrochemical performance due to the contributions from electric double-layer capacitance and pseudocapacitance.

High-Performance Washable PM Filter Fabricated with Laser-Induced Graphene.

This study demonstrates a novel application of laser-induced graphene (LIG) as a reusable conductive particulate matter (PM) filter. Four types of LIG-based filters were fabricated based on the laser-induced pyrolysis of thin polyimide (PI) sheets, each pyrolyzed on either a single side or both sides, with or without densification. The LIG filters exhibited a high removal efficiency while maintaining minimal pressure drop compared to a commercial fiberglass filter.

Heat Scanning for the Fabrication of Conductive Fibers.

Conductive fibers are essential building blocks for implementing various functionalities in a textile platform that is highly conformable to mechanical deformation. In this study, two major techniques were developed to fabricate silver-deposited conductive fibers. First, a droplet-coating method was adopted to coat a nylon fiber with silver nanoparticles (AgNPs) and silver nanowires (AgNWs).

Laser Pyrolysis of Imprinted Furan Pattern for the Precise Fabrication of Microsupercapacitor Electrodes.

The design or dimension of micro-supercapacitor electrodes is an important factor that determines their performance. In this study, a microsupercapacitor was precisely fabricated on a silicon substrate by irradiating an imprinted furan micropattern with a CO laser beam under ambient conditions. Since furan is a carbon-abundant polymer, electrically conductive and porous carbon structures were produced by laser-induced pyrolysis.

Hierarchically Structured Laser-Induced Graphene for Enhanced Boiling on Flexible Substrates.

Thermal management problems in high-power flexible electronics are exacerbated by the design complexity and requirement of stringent temperature control to prevent skin burns. Thus, effective heat dissipation methods applicable to flexible electronics on polymer substrates are an essential device design component. Accordingly, this study investigates the pool boiling heat transfer characteristics and potential enhancements, enabled by laser-induced graphene (LIG), which is both highly porous and bendable.

Development of a Protein Microarray Chip with Enhanced Fluorescence for Identification of Semen and Vaginal Fluid.

The detection of body fluids has been used to identify a suspect and build a criminal case. As the amount of evidence collected at a crime site is limited, a multiplex identification system for body fluids using a small amount of sample is required. In this study, we proposed a multiplex detection platform using an Ag vertical nanorod metal enhanced fluorescence (MEF) substrate for semen and vaginal fluid (VF), which are important evidence in cases of sexual crime.

Laser-Induced Reduction of Graphene Oxide by Intensity-Modulated Line Beam for Supercapacitor Applications.

Supercapacitors are irreplaceable energy-storage devices for high power output and rapid charge/discharge of electrical energy. In this study, the laser-based fabrication of reduced graphene oxide (rGO) electrodes for supercapacitors is demonstrated with several new features of laser irradiation. A conventional CO laser irradiation system is equipped with (1) a nitrogen blower to avoid combustion of the GO paper, (2) a cylindrical lens for producing a wide line beam, and (3) an optical chopper system for generating an intensity-modulated laser beam.

Effect of Enhanced Thermal Stability of Alumina Support Layer on Growth of Vertically Aligned Single-Walled Carbon Nanotubes and Their Application in Nanofiltration Membranes.

We investigate the thermal stability of alumina supporting layers sputtered at different conditions and its effect on the growth of aligned single-walled carbon nanotube arrays. Radio frequency magnetron sputtering of alumina under oxygen-argon atmosphere produces a Si-rich alumina alloy film on a silicon substrate. Atomic force microscopy on the annealed catalysts reveals that Si-rich alumina films are more stable than alumina layers with low Si content at the elevated temperatures at which the growth of single-walled carbon nanotubes is initiated.

Directed dewetting of amorphous silicon film by a donut-shaped laser pulse.

Irradiation of a thin film with a beam-shaped laser is proposed to achieve site-selectively controlled dewetting of the film into nanoscale structures. As a proof of concept, the laser-directed dewetting of an amorphous silicon thin film on a glass substrate is demonstrated using a donut-shaped laser beam. Upon irradiation of a single laser pulse, the silicon film melts and dewets on the substrate surface.

Highly flexible, all solid-state micro-supercapacitors from vertically aligned carbon nanotubes.

We report a highly flexible planar micro-supercapacitor with interdigitated finger electrodes of vertically aligned carbon nanotubes (VACNTs). The planar electrode structures are patterned on a thin polycarbonate substrate with a facile, maskless laser-assisted dry transfer method. Sputtered Ni is used to reduce the in-plane resistance of the VACNT electrodes.

In situ monitoring of laser-assisted hydrothermal growth of ZnO nanowires: thermally deactivating growth kinetics.

The laser-assisted hydrothermal growth kinetics of a cluster of ZnO nanowires are studied based on optical in situ growth monitoring. The growth yields are orders of magnitude higher than those of conventional hydrothermal methods that use bulk heating. This remarkable improvement is attributed to suppression of precursor depletion occurring by homogeneous growth reactions, as well as to enhanced mass transport.

Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer.

In situ TEM near-field optical probing of nanoscale silicon crystallization.

Laser-based processing enables a wide variety of device configurations comprising thin films and nanostructures on sensitive, flexible substrates that are not possible with more traditional thermal annealing schemes. In near-field optical probing, only small regions of a sample are illuminated by the laser beam at any given time. Here we report a new technique that couples the optical near-field of the laser illumination into a transmission electron microscope (TEM) for real-time observations of the laser-materials interactions.

Growth kinetics of vertically aligned carbon nanotube arrays in clean oxygen-free conditions.

Vertically aligned carbon nanotubes (CNTs) are an important technological system, as well as a fascinating system for studying basic principles of nanomaterials synthesis; yet despite continuing efforts for the past decade many important questions about this process remain largely unexplained. We present a series of parametric ethylene chemical vapor deposition growth studies in a "hot-wall" reactor using ultrapure process gases that reveal the fundamental kinetics of the CNT growth. Our data show that the growth rate is proportional to the concentration of the carbon feedstock and monotonically decreases with the concentration of hydrogen gas and that the most important parameter determining the rate of the CNT growth is the production rate of active carbon precursor in the gas phase reaction.

pH-tunable ion selectivity in carbon nanotube pores.

The selectivity of ion transport in nanochannels is of primary importance for a number of physical, chemical, and biological processes ranging from fluid separation to ion-channel-regulated cellular processes. Fundamental understanding of these phenomena requires model nanochannels with well-defined and controllable structural properties. Carbon nanotubes provide an ideal choice for nanofluidic studies because of their simple chemistry and structure, the atomic scale smoothness and chemical inertness of the graphitic walls, and the tunability of their diameter and length.

Mechanism and kinetics of growth termination in controlled chemical vapor deposition growth of multiwall carbon nanotube arrays.

We have investigated growth kinetics of multiwall carbon nanotube (MWCNT) arrays produced by catalytic thermal decomposition of ethylene gas in hydrogen, water, and argon mixture. The MWCNT growth rate exhibits a nonmonotonic dependence on total pressure and reaches a maximum at approximately 750 Torr of total pressure. Water concentrations in excess of 3000 ppm lead to the decrease in the observed growth rate.