A chemiresistive sensor array based on polyaniline nanocomposites and machine learning classification

• Jiri Kroutil,
• Alexandr Laposa,
• Ali Ahmad,
• Jan Voves,
• Vojtech Povolny,
• Ladislav Klimsa,
• Marina Davydova and
• Miroslav Husak

Beilstein J. Nanotechnol. 2022, 13, 411–423, doi:10.3762/bjnano.13.34

• sensing mechanism of nanocomposite layers based on PANI was discussed in [10]. Polyaniline is known as one of the most famous p-type conductive polymers. During the exposure to a reducing gas (NH3), the emeraldine salt form of polyaniline is converted to the emeraldine base form leading to an increase in

• concentration (50 ppm) as well as incomplete reversibility. When the operating temperature increased up to 80 °C, the sensing layers showed an at least three times lower response to ammonia in contrast to the room temperature measurements (Figure 7), but with almost complete reversibility (Figure 8). The gas

Morphology-driven gas sensing by fabricated fractals: A review

• Vishal Kamathe and
• Rupali Nagar

Beilstein J. Nanotechnol. 2021, 12, 1187–1208, doi:10.3762/bjnano.12.88

• structure, inherent rough surfaces, and gaps acting as diffusion channels. Gas-sensing mechanism of fractal structures There are a number of models to explain the function of conductometric SMO gas sensors. For instance, electron depletion layer (for n-type materials) or hole accumulation layer theory (for

Selective gas detection using Mn₃O₄/WO₃ composites as a sensing layer

• Yongjiao Sun,
• Zhichao Yu,
• Wenda Wang,
• Pengwei Li,
• Gang Li,
• Wendong Zhang,
• Lin Chen,
• Serge Zhuivkov and
• Jie Hu

Beilstein J. Nanotechnol. 2019, 10, 1423–1433, doi:10.3762/bjnano.10.140

• accurate detection. Sensing mechanism It is commonly accepted that the gas sensing mechanism of n-type WO3 is based on the surface reaction between the adsorbed oxygen ions and target gas molecules [31][32][33]. When exposed to air, the oxygen molecules are adsorbed on the surface and capture electrons

Hydrophilicity and carbon chain length effects on the gas sensing properties of chemoresistive, self-assembled monolayer carbon nanotube sensors

• Juan Casanova-Cháfer,
• Carla Bittencourt and
• Eduard Llobet

Beilstein J. Nanotechnol. 2019, 10, 565–577, doi:10.3762/bjnano.10.58

• response and selectivity. This would make the detection of polar and nonpolar gas species employing low-power gas sensors easier, even under fluctuating ambient moisture conditions. Keywords: carbon length chain; gas sensing mechanism; hydrophilicity; hydrophobicity; multiwall carbon nanotubes (MWCNTs

• quantitative XPS results indicating that the Au content was 5.7 wt % in these samples). A monomodal distribution of Au nanoparticles is obtained with average diameter of about 4 nm. The gold nanoparticles appear very close one to another (typically 10 nm apart), which will affect the gas sensing mechanism, as

• chain. The gas sensing mechanism for detecting ethanol is, once more, related to hydrogen bonding (see Figure 6e,f). It is well-known that hydrophilic groups present more affinity to polar compounds (e.g., ethanol) than hydrophobic radicals. This concept can explain why the short hydrophilic chain thiol

Gas-sensing behaviour of ZnO/diamond nanostructures

• Marina Davydova,
• Alexandr Laposa,
• Jiri Smarhak,
• Alexander Kromka,
• Neda Neykova,
• Josef Nahlik,
• Jiri Kroutil,
• Jan Drahokoupil and
• Jan Voves

Beilstein J. Nanotechnol. 2018, 9, 22–29, doi:10.3762/bjnano.9.4

• amount of adsorbed oxygen on the sensor surface, and ii) relatively low working temperature of 150 °C. For the purpose of understanding the decrease or increase in resistivity of our sensor devices, the gas sensing mechanism has to be discussed. After exposing the sensors to oxidizing gas (i.e., NO2

• ), the electric resistance decreases for p-type H-terminated NCD (Figure 2b); on the contrary, with n-type ZnO the resistance increases (Figure 2d). In general, this response behaviour is in concordance with the typical gas sensing mechanism of p- and n-type semiconductors [22][31]. The gas sensing

Nanocrystalline TiO₂/SnO₂ heterostructures for gas sensing

• Barbara Lyson-Sypien,
• Anna Kusior,
• Mieczylaw Rekas,
• Jan Zukrowski,
• Marta Gajewska,
• Katarzyna Michalow-Mauke,
• Thomas Graule,
• Marta Radecka and
• Katarzyna Zakrzewska

Beilstein J. Nanotechnol. 2017, 8, 108–122, doi:10.3762/bjnano.8.12

• behavior begins to prevail upon water desorption/oxygen adsorption depends on the TiO2/SnO2 composition. The electrical resistance of sensing materials exhibits a power-law dependence on the H2 partial pressure. This allows us to draw a conclusion about the first step in the gas sensing mechanism related

Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Gennaro Cassano,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2017, 8, 82–90, doi:10.3762/bjnano.8.9

• advantageous properties such as good sensitivity under ambient conditions and easy preparation [25]. The fundamental process of the gas-sensing mechanism, holding the MOx-based sensing material at elevated temperatures above 300 °C, is the reaction of the surrounding gases with the oxygen of the MOx layer

• similar gas sensing layers (e.g., Pd-sensitized ZnO nanobeads [48]). This is probably because of the lower film porosity. A high film porosity is necessary to obtain better results with this HCs gas sensing mechanism [49][50]. To evaluate and compare the cross-sensitivity of the unmodified and Pd-modified

Ammonia gas sensors based on In₂O₃/PANI hetero-nanofibers operating at room temperature

• Qingxin Nie,
• Zengyuan Pang,
• Hangyi Lu,
• Yibing Cai and
• Qufu Wei

Beilstein J. Nanotechnol. 2016, 7, 1312–1321, doi:10.3762/bjnano.7.122

• final response reached 47.42, which was about 89% of the first test. Hence, the In2O3/PANI-2 nanofibers sensor showed good repeatability and reversibility. Gas sensing mechanism It is well known that the chemical sensors are composed of two parts, an active part and a transduction part, whose function

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

• Elena Dilonardo,
• Michele Penza,
• Marco Alvisi,
• Cinzia Di Franco,
• Francesco Palmisano,
• Luisa Torsi and
• Nicola Cioffi

Beilstein J. Nanotechnol. 2016, 7, 22–31, doi:10.3762/bjnano.7.3

• active layer in low-cost chemiresistive gas sensors, due to their high sensitivity to gaseous analytes and easy production. The gas-sensing mechanism of MOS-based gas sensors is based on receptor and transducer functions [3]. Specifically, the first regards the recognition of a gaseous analyte by an

• used as a gas-sensing material because of its remarkable properties, such as high chemical and thermal stability, wide direct band gap, chemical sensitivity to different adsorbed gases, highly mobile conduction carriers, non-toxicity and low cost [18][19][20]. Moreover, since gas-sensing mechanism is a

• 550 °C to illustrate the moments of gas input and gas stop. As written in the Introduction, the gas-sensing mechanism of ZnO involves chemical and electronic interaction between the gas and the ZnO at the oxide surface, revealed as the resistance variation of the sensing materials. Charge transfer

Effects of palladium on the optical and hydrogen sensing characteristics of Pd-doped ZnO nanoparticles

• Anh-Thu Thi Do,
• Hong Thai Giang,
• Thu Thi Do,
• Ngan Quang Pham and
• Giang Truong Ho

Beilstein J. Nanotechnol. 2014, 5, 1261–1267, doi:10.3762/bjnano.5.140

• of 65% RH, the linear dependence of the sensitivity of the Pd/ZnO-based sensor on hydrogen concentrations in the range of 0–25% LEL was observed as shown in Figure 4b. The gas sensing mechanism usually accepted for semiconductor sensors explains the functionality due to reactions of hydrogen with the

Investigation on structural, thermal, optical and sensing properties of meta-stable hexagonal MoO₃ nanocrystals of one dimensional structure

• Angamuthuraj Chithambararaj and
• Arumugam Chandra Bose

Beilstein J. Nanotechnol. 2011, 2, 585–592, doi:10.3762/bjnano.2.62

• counts/ppm for λmax = 684, 764 and 935 nm, respectively. From the plot, the maximum sensitivity is seen for λmax = 684 nm. Here, it is proposed that the gas sensing mechanism follows the changes in the refractive index and evanescent wave absorption. For h-MoO3, the oxygen vacancies and interstitial

• linearly as a function of ethanol concentration in the range of 0 to 500 ppm. In the present study, changes in the refractive index and the evanescent wave absorption phenomenon were proposed to explain the gas sensing mechanism. The reaction between ethanol gas and the chemisorbed oxygen (O2−, O− and O2