1wileyonlinelibrary.com oxidizing or reducing gases while operating at room temperature (RT). [16][17][18] Since then, electron conductive polymer-based sensors have attracted rapidly growing interest. [ 19 ] Particularly, the polymers with amino groups have been reported as promising candidates for CO 2 sensing, but in practice they suffer from poisoning with carbamates and therefore failed to fi ll the gap in the CO 2 gas sensor sector. [ 20,21 ] As a consequence, sensing of inert CO 2 gas is still performed with infrared spectroscopy, owing to trade-offs between the technological and economical factors, and having limited portability. Recently, poly(ionic liquid)s (PILs), a unique type of functional polyelectrolytes composed of ionic liquid repeating units chosen from structural diversity of the cation/anion-repertoire of ionic liquid chemistry, have been synthesized. [22][23][24] Their physical properties can be easily and broadly adjusted by the choice of the anion-cation pair. For example, structurally well-designed PILs are capable of reversible CO 2 capture and are showing high interfacial activity to bind various surfaces of metals, carbons, and to ionically interact with charged species via electrostatic repulsion or complexation. [25][26][27][28] Others demonstrated the ability of resistive CO 2 sensing with carbon nanotubes (CNTs) wrapped with poly[1-(p-vinylbenzyl)-3-methyl-imidazolium tetrafl uoroborate], P[VBTMA] [BF 4 ]. [ 29 ] They show a high sensitivity to low concentrations of CO 2 in oxygen-free atmospheres, but the response saturates already at 50 ppm, which is much lower than the normal CO 2 concentration level in fresh air (250 ppm) and thus lacks of practical application. Therefore, transforming the CO 2 sorption capacity of PILs into a chemoresistive sensor operating in real conditions, i.e., 21 vol% of oxygen and 50% relative humidity (rh), in the presence of 400 ppm [ 30 ] of CO 2 at RT requires a new structural model and additionally an understanding of the intrinsic interaction between organic and inorganic building blocks and their impact on the overall properties of such composites. Among different candidates, poly [( p -vinylbenzyl nanoparticles-both of which are intrinsically insulating materials-are utilized as building blocks, taking full advantage of the electrostatic interaction at their interface to boost the overall conductivity of composites at room temperature. To rationalize this unique behavior, the charge transport mechanism is studied using impedance spectroscopy. It is found fi nd that, for the composites with La 2 O 2 CO 3 content of 60-80 wt%, the interfacial effect becomes dominant and leads to the formation of conduction channels with increased mobility of [PF 6 ] − anions. These composites show further increase of the conductivity when exposed to pulses of CO 2 between 150 and 2400 ppm at room temperature in a relative humidity of 50%. This work therefore provides a simple strategy to achieve an enhancement of the electrical properties required for the utilizat...

Alignment of nanowires over a large area of flat and patterned substrates is a prerequisite to use their collective properties in devices such as gas sensors. In this work, uniform single-crystalline ultrathin W18 O49 nanowires with diameters less than 2 nm and aspect ratios larger than 100 have been synthesized, and, despite their flexibility, assembled into thin films with high orientational order over a macroscopic area by the Langmuir-Blodgett technique. Alignment of the tungsten oxide nanowires was also possible on top of sensor substrates equipped with electrodes. Such sensor devices were found to exhibit outstanding sensitivity to H2 at room temperature.

We report a light, flexible, and low-power poly(ionic liquid)/alumina composite CO2 sensor. We monitor the direct-current resistance changes as a function of CO2 concentration and relative humidity and demonstrate fast and reversible sensing kinetics. Moreover, on the basis of the alternating-current impedance measurements we propose a sensing mechanism related to proton conduction and gas diffusion. The findings presented herein will promote the development of organic/inorganic composite CO2 gas sensors. In the future, such sensors will be useful for numerous practical applications ranging from indoor air quality control to the monitoring of manufacturing processes.

Organic–Inorganic hybrids – from individual building blocks to an artificial carbon cycle and beyond.