SAM Functionalized ZnO Nanowires for Selective Acetone Detection: Optimized Surface Specific Interaction Using APTMS and GLYMO Monolayers

Abstract

In modern days, self‐assembled monolayer (SAM) functionalized surfaces represent an interesting tool for the development of ultrasensitive and selective sensing platforms for the detection of chemical substances such as biomolecules and gases. The ability of SAM to generate different functional groups on a single surface such as zinc oxide (ZnO) can be used to immobilize biomolecules and detect different analytes such as gases, proteins, etc. Herein, SAM functionalized ZnO NW‐based sensors are developed for acetone exhaled breath analysis. ZnO NWs are synthesized using a vapor–liquid–solid mechanism and their functionalization is done with two different SAMs, i.e., (3‐aminopropyl)trimethoxysilane (APTMS) and 3‐glycidoxypropyltrimethoxysilane (GLYMO). The enhancement in the electron depletion layer resistance (and also width) due to the capturing of electrons from the ZnO NWs surface by APTMS and GLYMO molecules is found to be the major reason in their superior sensing performances. The amine (–NH2) groups of APTMS monolayer enhance the sensors selectivity toward acetone due to their reactions with acetone molecules, which produce imine in addition to water molecules. Moreover, after the functionalization with APTMS SAMs, the detection limits of the sensors are improved from 6 to 0.5 ppm, which makes these devices potential candidates for acetone exhaled breath analysis.

New Insights towards High-Temperature Ethanol-Sensing Mechanism of ZnO-Based Chemiresistors

“…The inset in Figure 6 a, demonstrating the difference between O 1s spectra taken in O 2 and O 2 /EtOH atmospheres, shows an increase in oxygen signal in the 531.5–533 eV region. In this region, the oxygen signals from different hydrocarbons containing oxygen, H 2 O and OH usually appear [ 42 ]. Similar signal increases can be observed in the case of O 2 /EtOH/H 2 O and O 2 /MeCHO atmospheres.…”

SnO2 -SiO2 1D Core-Shell Nanowires Heterostructures for Selective Hydrogen Sensing

“…This reduction of the gassensing response in humid environment for SMOX-based gas sensors is due to the competition of adsorption between the analyte gas and the water molecules as reported earlier. 8,37 Figure 3g and Figure S5b 3g). The sensor fabricated with SnO 2 -SiO 2 /60 CSNWs shows the best response among all the fabricated sensors.…”

“…The calibration curves, response vs concentration follow a typical power-law relation (in agreement with the eq 3) for SMOX-sensors, further confirming the absence of any saturation process. 8,37 The sensors detection limit is calculated while considering the minimum response value of 1 in eq 3. The values of different parameters calculated by the power-law fits are summarised in Table S2.…”

“…10,[32][33][34][35] These 1D nanowires provide a large number of active surface sites for the adsorption of gas molecules due to their high surface area. [36][37][38][39][40] For examples, one of our recent study has shown that SnO 2 based C-S heterostructures such as SnO 2 -NiO showed improved properties towards hydrogen gas-sensing as compared to pristine SnO 2 nanostructures. 8 In that case, the enhanced sensing-response after the NiO-coatings was assigned to the formation of a p-n junction and to the modulation of space charge region.…”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…To this light, Kim et al and Singh et al demonstrated an exceptional acetone sensitivity (refer to Table 1 ) of Co 3 O 4 NPs modified SnO 2 NWs and self-assembled monolayer (SAM) functionalized ZnO NWs [ 70 , 71 ]. These sensory materials can be synthesized via vapor–liquid–solid (VLS), sol–gel, and thermal annealing processes to detect acetone with an LOD of 0.5 ppm.…”