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We report the properties of a hydrogen (H2) gas sensor based on platinum (Pt)-coated carbon nanotubes (CNTs) in this paper. To fabricate the Pt-CNT composite sensor, a highly aligned CNT sheet was prepared on a glass substrate from a spin-capable CNT forest, followed by electrobeam (e-beam) deposition of Pt layers onto the CNT sheet. To investigate the effect of Pt on the response of the sensor, Pt layers of different thicknesses were deposited on the CNT sheets. A Pt thickness of 6 nm yielded the highest response for H2 detection, whereas Pt layers thinner or thicker than 6 nm led to a reduction of the surface area for gas adsorption and, consequently, decreased response. The Pt-CNT composite sensor detects H2 concentrations of 3-33% at room temperature and shows reproducible behavior with fast response and recovery times.

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In addition, plasma plays an important role in many fields including space propulsion and biomedical technology. [4-6] Cathode tubes and plasma generation require an external power supply equipment, however unfortunately this equipment is not portable because of its heavy weight and large volume. Therefore, high voltage applications have severe limitations in harsh environments such as space, battlegrounds, and backcountry, where there is no electricity supply. Triboelectric nanogenerators (TENGs) [7-11] based on a working mechanism of both triboelectrification and electrostatic induction can generate electricity from mechanical movements in our surroundings or human motion without the need for an external power supply. [12-16] Until now, the power generated by TENG has been applied as an energy source for body-implantable medical devices, light-emitting diodes, liquid crystal displays, sensors, and low powerconsuming electronic devices. [11,17-20] Considering self-powered high voltage and portability, TENG can be regarded as an ideal driving source for high voltage applications. In this work, we propose a serrated electrode-based TENG (SE-TENG) that generates ultrahigh power output based on the spark discharge to drive high voltage-operating devices directly. When two different friction materials are in contact and then An ultrahigh power output from a triboelectric nanogenerator (TENG) with a serrated electrode in a low-frequency contact-separation mode which is able to directly drive high voltage-operating devices without the need for an external power supply is demonstrated. When a serrated electrode-based TENG (SE-TENG) is driven, the microstructurally serrated electrode creates a spark discharge in the gap between the serrated electrode and a wire, resulting in tremendously boosted triboelectric power output. Based on the spark discharge phenomenon, a boost adaptor is designed to secondarily boost the triboelectric power output performance, and consequently an ultrahigh triboelectric output voltage of 5 kV and current density of 2 A m −2 are achieved. The boost adaptor concept can be applied to any typical TENG for achieving higher power-generating performance. Finally, two high voltage applications, a Crookes tube and plasma generation, are demonstrated using the SE-TENG and boost adaptor without any external power supply equipment. The ultrahigh power-generating SE-TENG based on the spark discharge phenomenon occurring in the unique electrode structure has considerable potential to operate high voltage applications directly in harsh environments where electricity cannot be supplied.

High strain biocompatible polydimethylsiloxane-based conductive graphene and multiwalled carbon nanotube nanocomposite strain sensors Appl. Phys. Lett. 102, 183511 (2013); 10.1063/1.4804580Graphene wrapped multiwalled carbon nanotubes dispersed nanofluids for heat transfer applications This paper reports highly flexible, transparent, conducting heaters based on multiwalled carbon nanotube (MWCNT) sheets. The MWCNT sheets were spun directly from a well-aligned MWCNT forest. The fabrication of the MWCNT sheet heater was quite simple and suitable for mass production, requiring only a one-step transferring process, in which the MWCNT sheet is drawn onto the target substrates. This study examined the parameters that affect the heat generation of the MWCNT sheet-based heater; input power, surface area, and thermal conductivity of the substrate. In particular, more effort was focused on how to increase the surface area and contact points between the individual MWCNTs; simple acid treatment and added metal nanoparticles increased the heat performance of the heater dramatically. Moreover, the heaters exhibited durability and flexibility against many bending cycles. Therefore, the MWCNT sheet-based heater can be used for versatile applications requiring transparency, conduction, and flexibility.