Double-side microcantilevers as a key to understand the adsorption mechanisms and kinetics of chemical warfare agents on vertically-aligned TiO2 nanotubes

Quantitative Structure–Activity Relationship of Nanowire Adsorption to SO2 Revealed by In Situ TEM Technique

“…Compared with the classical Langmuir model, the Langmuir–Freundlich equation introduces a heterogeneity exponent to improve the fitting accuracy (Figure S8). On the basis of the Clausius–Clapeyron equation, − the −Δ H ° values of the two samples were calculated to be 133.6 kJ/mol (ZnO-100 nm) and 38.9 kJ/mol (ZnO-500 nm). According to physicochemical theory, the high −Δ H ° value of 133.6 kJ/mol suggests that the ZnO-100 nm sample exhibits high reactivity toward the SO 2 molecules, allowing a chemical reaction to occur.…”

3D Core–Shell TiO2@MnO2 Nanorod Arrays on Microcantilevers for Enhancing the Detection Sensitivity of Chemical Warfare Agents

“…DMMP in the gas phase is initially adsorbed faster when the initial concentration increases (better response time of the sensor). Low DMMP concentrations can result in a slowdown of molecular diffusion through the gas film to the internal surface (film diffusion) of the microcantilever . Moreover, when the concentration of DMMP vapor decreases, the probability that a DMMP molecule encounters the NR surface can decline, contributing also to a decrease in the response time of the sensor.…”

“…The functionalization can be realized only after the microcantilever fabrication due to the harsh manufacturing conditions that may require technical operations (e.g., the chemical inkjet printing technique). In addition, molecules may not be stable at a high temperature and over a long period of time, and surface functionalization of microcantilevers must be performed only on one side of the microcantilever to allow the readout of the bending signal. , The second way consists in nanostructuring the microcantilever surface with various nanostructures such as titanium dioxide (TiO 2 ) nanotubes (NTs) ,, and nanorods (NRs), copper oxide (CuO) NRs, mesoporous silica nanoparticles or films, ZnO nanowires, carbon NTs, and metal–organic frameworks (MOFs) . This strategy offers a large increase in the surface area leading to capture a high amount of molecules on the microcantilever surface.…”

“…To the best of our knowledge, such 3D composites and more particularly TiO 2 NR arrays decorated with MnO 2 nanoflakes have not been studied and synthetized on the surface of a microcantilever as high-sensing materials. The process developed in this study has the advantages (i) of involving two facile and short-time syntheses; (ii) of guaranteeing the reflection of the laser from the back side of the microcantilever; (iii) of using both materials (TiO 2 and MnO 2 ) having a good chemical and thermal stability; − (iv) of exploiting TiO 2 NRs, which exhibited a good affinity with organophosphorous compounds, ,,− as a support to create a 3D nanostructure by covering TiO 2 NRs with thin MnO 2 nanostructures in order to increase the microcantilever surface area and of avoiding the effect of mass overloading on the microcantilever, which could be detrimental for the sensor sensitivity; (v) of developing nanostructures with a low dead volume in order to fix a higher amount of molecules; and (vi) of taking advantage of MnO 2 , which has recently shown a high reactivity to OPs. Manganese oxide indeed showed strong interactions with OPs due to electron-rich phosphoryl oxygen, Brønsted acid sites [surface-bound hydroxyl groups (Mn–OH)], and Lewis acid sites (Mn 4+ ). − In this work, TiO 2 NRs, which typically have large surface areas, have been decorated with MnO 2 ultrathin nanoflakes in order to increase the active surface of capture and also to exploit MnO 2 as a highly reactive material for the low-trace vapor-phase detection of DMMP.…”

Fluorophenol-Containing Hydrogen-Bond Acidic Polysiloxane for Gas Sensing-Synthesis and Characterization

“…Among them, techniques allowing for the construction of cheap and compact gas analyzers (e.g., that are possible to be used as on-board equipment for unmanned aerial vehicles) are of particular interest. The above requirements are well met by gravimetric gas sensors based on a variety of acoustoelectric transducers, such as quartz crystal microbalances (QMB) [ 5 ], surface acoustic wave (SAW) devices utilizing both Rayleigh and Love waves [ 6 , 7 ], or microcantilever transducers [ 8 , 9 ].…”