The gas sensor response of tin monoxide micro-disks, functionalized with noble metal nanoparticles (Pd and Ag), to NO 2 , H 2 and CO were studied by monitoring changes in their resistance upon exposure to the various gases. The tin monoxide, with unusually low Sn oxidation state, was synthetized by carbothermal reduction. Surface modification by Pd and Ag catalysts was achieved by coating the micro-disks by metallic nanoparticle dispersions, prepared by the polyol reduction process, followed by thermal treatment. SEM and TEM analysis showed nanoparticles to be well-dispersed over the SnO surfaces. The decorated SnO micro-disks exhibited high sensor response to reducing gases such as H 2 and CO. On the other hand, the catalytic particles tended to reduce the sensor response to oxidizing

Electrolyte-gated (EG) transistors, based on electrolyte gating media, are powerful device structures to modulate the charge carrier density of materials by orders of magnitude, at relatively low operating voltages (sub-2 V). Tungsten trioxide (WO 3 ) is a metal oxide semiconductor well investigated for applications in electrochromism, sensing, photocatalysis, and photoelectrochemistry. In this work, we report on EG transistors making use of mesoporous nanostructured WO 3 thin films easily permeated by the electrolyte as the transistor channel and bis(trifluoromethylsulfonyl)imide ([TFSI])-based ionic liquids as the gating media. The WO 3 EG transistors operate at ca. 1 V. Using a combination of cyclic voltammetry, X-ray diffraction, and transistor performance characterizations, complemented by spectroscopic (Raman and infrared) investigations, we correlate the metal oxidation state and the charge transport properties of the metal oxide, shedding light on the doping process in electrically biased WO 3 nanostructured thin films exposed to electrolytes.

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Electrolyte-gated transistors hold promise for applications in printable and flexible electronics.