A room-temperature hydrogen gas (H2) sensor was successfully fabricated by dispersion of palladium nanoparticles (Pd NPs) on graphene sheets (GRs) (hereafter referred to as “Pd NPs/GRs”). GRs and Pd NPs were synthesized by chemical vapor deposition technique and by polyol process, respectively. A colloidal solution of Pd NPs with an average diameter of 11 nm was then dispersed onto the GRs by spin coating technique. The density of dispersed Pd NPs on GRs was controlled by varying the volume of the dispersed solution within the range of 50 – 150 μL. The fabricated Pd NPs/GRs sensors exhibited a high sensitivity for H2 gas with a concentration of 1500 – 6000 ppm at room temperature. Upon H2 exposure, the Pd NPs/GRs sensors showed an increase in electrical resistance, which could easily be measured. The relationship between sensor response and H2 concentration is in correspondence with the Langmuir adsorption model. The H2 detection limit is estimated to be 1 ppm. The results demonstrate that the Pd NPs/GRs sensor is an easily fabricated, but very effective means for room-temperature detection of H2at ppm level.
Poly(methyl methacrylate) (PMMA) and thiophene-coated single-walled carbon nanotubes (SWNTs) were fabricated for use in volatile organic compound (VOC) detection. Pristine SWNTs were separately coated with PMMA (PMMA/SWNTs) and thiophene (thiophene/SWNTs) by spincoating. Pristine SWNTs showed the highest response to methanol, while PMMA/SWNTs enabled 5.4-fold improved dichloromethane detection and thiophene/SWNTs enabled 1.4-fold improved acetone detection compared with pristine SWNTs. The sensor response of PMMA/SWNTs to dichloromethane and that of thiophene/SWNTs to acetone can be attributed to the Hildebrand solubility parameter (HSP). The more similar the HSP, the higher the sensor response. The sensor response of pristine SWNTs to methanol is related to the diffusion coefficient and molecular size. The relationships between the vapor concentration and sensor response of PMMA/SWNTs to dichloromethane and thiophene/SWNTs to acetone are based on Henry's adsorption isotherm, while that of pristine SWNTs to methanol is based on the Henry-clustering model. Principal component analysis (PCA) results show that dichloromethane, acetone, and methanol were successfully discriminated.
A chemosensor based on a cyanoacrylic (DTP-C) consists of dithieno[3,2-b;2’,3’-d]pyrrole(DTP) as a chromophore and a cyanoacrylic moiety as an ionophore which linked by aromatic system. DTP-C demonstrates the response of complex with Fe(II) in dimethylformamide (DMF) solution. The binding mode of Fe(II)/DTP-C complex was characterized using UV-Visible and fluorescence spectroscopy. In addition, the effect of various MES buffer was then studied at 5%, 10%, 15% and 20% v/v in Fe(II)/DTP-C complex which the appropriate ratiomatric of MES buffer is 10%. The enhancement of Fe(II) concentration indicate a decrease emission intensity while the addition of buffer concentrations found to increase in the intensity. Moreover, quantum chemical calculations were used to study the electronic and optical properties of the molecular structure of DTP-C under the density functional theory.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.