Employing Halogen Bonding Interactions in Chemiresistive Gas Sensors

This paper reports the use of halogen bonding interactions for gas-phase detection of pyridine in SWCNT-based chemiresistive sensors with sub-ppm theoretical detection limits. The chemiresistors are prepared by solvent-free ball-milling of single-walled carbon nanotubes (SWCNTs) and aryl halide-based selectors, compression into a pellet, and subsequent mechanical abrasion between gold electrodes on paper. The sensing responses reflect halogen bonding trends, with few exceptions. The predominant signal transduction mechanism is likely attributed to swelling of the insulating haloarene matrix.National Institutes of Health (U.S.) (National Cancer Institute (U.S.). Ruth L. Kirschstein National Research Service Award F32CA157197

Wireless gas detection with a smartphone via rf communication

Chemical sensing is of critical importance to human health, safety, and security, yet it is not broadly implemented because existing sensors often require trained personnel, expensive and bulky equipment, and have large power requirements. This study reports the development of a smartphone-based sensing strategy that employs chemiresponsive nanomaterials integrated into the circuitry of commercial near-field communication tags to achieve non-line-of-sight, portable, and inexpensive detection and discrimination of gas-phase chemicals (e.g., ammonia, hydrogen peroxide, cyclohexanone, and water) at part-per-thousand and part-per-million concentrations.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract W911NF-13-D-0001)Deshpande Center for Technological InnovationNational Institutes of Health (U.S.) (National Cancer Institute (U.S.) Ruth L. Kirschstein National Research Service Award F32CA157197

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future

Chemiresistive sensors are becoming increasingly important as they offer an inexpensive option to conventional analytical instrumentation, they can be readily integrated into electronic devices, and they have low power requirements. Nanowires (NWs) are a major theme in chemosensor development. High surface area, interwire junctions, and restricted conduction pathways give intrinsically high sensitivity and new mechanisms to transduce the binding or action of analytes. This Review details the status of NW chemosensors with selected examples from the literature. We begin by proposing a principle for understanding electrical transport and transduction mechanisms in NW sensors. Next, we offer the reader a review of device performance parameters. Then, we consider the different NW types followed by a summary of NW assembly and different device platform architectures. Subsequently, we discuss NW functionalization strategies. Finally, we propose future developments in NW sensing to address selectivity, sensor drift, sensitivity, response analysis, and emerging applications

Solid Aluminum Borohydrides for Prospective Hydrogen Storage

Metal borohydrides are intensively researched as highcapacity hydrogen storage materials. Aluminum is a cheap, light andabundant element and Al3+ can be a template for reversibledehydrogenation. However, Al(BH4)3, containing 16.9 weight % ofhydrogen, has a low boiling point, is explosive on air and has poorstorage stability. We present a new family of mixed-cationborohydrides M[Al(BH4)4], all solid at ambient conditions. Theirthermal decomposition properties show diverse behavior: Al(BH4)3 isreleased for M = Li+, Na+, while heavier derivatives evolve hydrogenand diborane. NH4[Al(BH4)4], containing protic and hydridichydrogens, has the lowest decomposition temperature of 35 °C andyields Al(BH4)3·NHBH and hydrogen. The decompositiontemperatures, correlated with cations' ionic potential, show thatM[Al(BH4)4] are in the most practical stability window. This family ofsolids with convenient and versatile properties puts aluminumborohydride chemistry in the mainstream of the hydrogen storageresearch, e.g. for the development of reactive hydride compositeswith increased hydrogen content

Hydrogen Storage Materials for Mobile and Stationary Applications: Current State of the Art

One of the limitations to the widespread use of hydrogen as an energy carrier is its storage in a safe and compact form. Herein, recent developments in effective high-capacity hydrogen storage materials are reviewed, with a special emphasis on light compounds, including those based on organic porous structures, boron, nitrogen, and aluminum. These elements and their related compounds hold the promise of high, reversible, and practical hydrogen storage capacity for mobile applications, including vehicles and portable power equipment, but also for the large scale and distributed storage of energy for stationary applications. Current understanding of the fundamental principles that govern the interaction of hydrogen with these light compounds is summarized, as well as basic strategies to meet practical targets of hydrogen uptake and release. The limitation of these strategies and current understanding is also discussed and new directions proposed

Screening of metal borohydrides by mechanochemistry and diffraction

Ay, there's the rub: The formation of cadmium-based borohydrides is screened by mechanochemical synthesis using various reactants in different ratios. Sequential in situ variable-temperature diffraction studies provide simultaneous information about composition, structure, decomposition pathways, and properties of the compounds. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim