An electronic textile-based NO 2 gas sensor was fabricated using commercial silk and graphene oxide (GO). It showed a fast response time and excellent sensing performance, which was simply accomplished by modifying the heat-treatment process. The heat treatment was conducted at 400 °C and different heating rates of 1, 3, and 5 °C/min. Compared with our previous research, the response time significantly decreased, from 32.5 to 3.26 min, and we found that the highest response was obtained with the sensor treated at a heating rate of 1 °C/min. To find the reason for this enhanced sensing performance, the morphology, structure, and chemical composition of the reduced GO (rGO) were investigated, depending on the thermal treatment process, using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. We also measured the temperature-dependent resistance of rGO, which was well described by the fluctuation-induced tunneling (FIT) model. These results revealed that the rGO thermally treated with 1 °C/ min of heating rate had the largest amount of oxygen groups. This means that the oxygen functional groups play an important role in NO 2 gas-sensing performance.

Demand for wearable and portable electronic devices has increased, raising interest in electronic textiles (e-textiles). E-textiles have been produced using various materials including carbon nanotubes, graphene, and graphene oxide. Among the materials in this minireview, we introduce e-textiles fabricated with graphene oxide (GO) coating, using commercial textiles. GO-coated cotton, nylon, polyester, and silk are reported. The GO-coated commercial textiles were reduced chemically and thermally. The maximum e-textile conductivity of about 10 S/cm was achieved in GO-coated silk. We also introduce an e-textile made of uncoated silk. The silk-based e-textiles were obtained using a simple heat treatment with axial tension. The conductivity of the e-textiles was over 100 S/cm.

We report on an electronic structure change of single-walled carbon nanotube (SWNT) on hexagonal boron nitride due to electron doping via high-pressure H 2 exposure. The fractional coverage of hydrogenated carbon atom is estimated to be at least θ=0.163 from the in situ I ds -V g measurements of the release process. Raman spectroscopy and x-ray photoelectron spectroscopy were carried out to support the in situ electrical measurements. In particular, we used the dissociative Langmuir-type model to yield the desorption coefficient k des by fitting it to the in situ electrical data. Finally, we applied this hydrogenation method to the SWNT network on the commercial Si/SiO 2 substrate to open the possibility of the scalable n-type semiconducting SWNT FETs.

Graphene oxide (GO)-coated silk-based electronic textiles (e-textiles) are of great interest and have high potential because of their advantages, including high electrical conductivity and flexibility. Although heat treatment of the GO-coated textiles at high temperatures results in e-textiles with high electrical conductivity, flexibility and structural stability are not guaranteed. Here, we demonstrate heat-treated GO-coated silk (HGS) at high temperatures (HTTs; 500, 600, 700, and 800 °C) with superior flexibility. For HGS800, the resistance change during bending remained under 1% even after 5000 cycles. We also investigated the charge transport mechanism of the HGSs and the interface between GO and the silk. The temperature-dependent resistivity of the HGSs from 8 to 300 K was clearly explained by the fluctuation-induced tunneling model for all HTTs. The temperature-dependent resistance of the interface follows multidimensional variable-range hopping. The conducting behavior of the HGSs was interpreted to be due to structural changes induced by HTT, based on scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction.