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

• electron microscopy, X-ray diffraction measurements and Raman spectroscopy. The gas sensing properties of the sensors based on i) NCD films, ii) ZnO nanorods, and iii) hybrid ZnO NRs/NCD structures were evaluated with respect to oxidizing (i.e., NO2, CO2) and reducing (i.e., NH3) gases at 150 °C. The

• hybrid ZnO NRs/NCD sensor showed a remarkably enhanced NO2 response compared to the ZnO NRs sensor. Further, inspired by this special hybrid structure, the simulation of interaction between the gas molecules (NO2 and CO2) and hybrid ZnO NRs/NCD sensor was studied using DFT calculations. Keywords

• remarkable semiconducting properties [20][21]. For instance, hydrogen-terminated NCD films exhibit changes in their surface conductivity in the presence of phosgene and could be utilized as an integrator-type gas sensor [22][23]. Up to now, many research groups have focused on nitrogen dioxide (NO2) sensing

The role of ligands in coinage-metal nanoparticles for electronics

• Ioannis Kanelidis and
• Tobias Kraus

Beilstein J. Nanotechnol. 2017, 8, 2625–2639, doi:10.3762/bjnano.8.263

• substituents (Me, MeO, Cl, or Br) in para-position to the thiol group reduced the conductivity compared to films of triphenylphosphine (PPh3) (Figure 3) and thiophenol (H)-capped gold nanocrystals. The electron-withdrawing nitro group (NO2) caused an increase in conductivity from 30 S/cm (PPh3-capped Au NPs

• oleylamine ligand shell with ammonium thiocyanate. Reprinted with permission from [30], copyright 2014 American Chemical Society. Conductivity as a function of the temperature in films of gold nanoparticles functionalized with thiophenol (H), with thiophenol para-substituted with nitro (NO2), methyl (Me

Metal oxide nanostructures: preparation, characterization and functional applications as chemical sensors

• Dario Zappa,
• Angela Bertuna,
• Elisabetta Comini,
• Navpreet Kaur,
• Nicola Poli,
• Veronica Sberveglieri and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2017, 8, 1205–1217, doi:10.3762/bjnano.8.122

• carriers results in an increase (for n-type semiconductors) or decrease (for p-type semiconductors) of the electrical conductance, respectively. For example, if we consider CO as target species to be detected we have (Equation 1) [14]: In the presence of oxidizing species such as NO2, the interaction on

• detection of the two target chemical compounds. Results are reported in Figure 10. As expected, each material behaves differently, and the working temperature has a strong effect on the response. Although some materials are more suited than others to detect CO or NO2, it is important to mention that all

• NO2. At lower temperatures (100 °C), NiO devices are too resistive to be measured in our test chamber. NiO has hardly been studied as a material for chemical sensors. Hence, there are only few reports about a tentative NO2 sensing mechanism. Zhang et. al. [24] pointed out that nickel vacancies could

Study of the correlation between sensing performance and surface morphology of inkjet-printed aqueous graphene-based chemiresistors for NO₂ detection

• F. Villani,
• C. Schiattarella,
• T. Polichetti,
• R. Di Capua,
• F. Loffredo,
• B. Alfano,
• M. L. Miglietta,
• E. Massera,
• L. Verdoliva and
• G. Di Francia

Beilstein J. Nanotechnol. 2017, 8, 1023–1031, doi:10.3762/bjnano.8.103

• . The device performances, in terms of relative conductance variations, upon exposure to NO2 at standard ambient temperature and pressure, are analysed. In addition, we examine the effect of the substrate morphology and, more specifically, of the ink/substrate interaction on the device performances, by

• chemiresistor have been analysed upon NO2 exposure at standard ambient temperature and pressure. Moreover, as comparison, inkjet-printed sensors have been manufactured on standard insulating substrates, namely alumina (Al2O3), and silicon dioxide (Si/SiO2). They have been characterized through gas sensing and

• , the I–V curve of the device D-P17 is reported in Figure 3. The sensing properties of the chemiresistors have been tested by exposing the devices to NO2, the analyte towards which LPE graphene is more specific [16]. In Figure 4a, the dynamic responses toward 1 ppm of NO2 for paper-based devices are

CVD transfer-free graphene for sensing applications

• Chiara Schiattarella,
• Sten Vollebregt,
• Tiziana Polichetti,
• Brigida Alfano,
• Ettore Massera,
• Maria Lucia Miglietta,
• Girolamo Di Francia and
• Pasqualina Maria Sarro

Beilstein J. Nanotechnol. 2017, 8, 1015–1022, doi:10.3762/bjnano.8.102

• have been investigated by exposing the devices to NO2, NH3 and CO, which have been selected because they are well-known hazardous substances. The concentration ranges have been chosen according to the conventional monitoring of these gases. The measurements have been carried out in humid N2 environment

• , setting the flow rate at 500 sccm, the temperature at 25 °C and the relative humidity (RH) at 50%. An increase of the conductance response has been recorded upon exposure towards NO2, whereas a decrease of the signal has been detected towards NH3. The material appears totally insensitive towards CO

• . Finally, the sensing selectivity has been proven by evaluating and comparing the degree of adsorption and the interaction energies for NO2 and NH3 on graphene. The direct-growth approach for the synthesis of graphene opens a promising path towards diverse applicative scenarios, including the

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

• . The NiO–graphene hybrids show good sensing capability for the reducing gases such as H2, NH3, H2S, NO2 [204]. In another work graphene nanosheet–NiO hybrids in combination with DNA are used as the high-performance nonenzymatic glucose sensors [205]. Recently graphene-wrapped NiO hybrids were prepared

• –graphene hybrids, was used as a high-performance NO2 gas sensor (Figure 8). Copper oxide (CuO) is also a p-type semiconductor. CuO–graphene composites have also been used as anode material for LIBs [211][215]. Mathesh et al. prepared GO hybrid materials consisting of Cu ions complexed with GO, where Cu2

α-((4-Cyanobenzoyl)oxy)-ω-methyl poly(ethylene glycol): a new stabilizer for silver nanoparticles

• Jana Lutze,
• Miguel A. Bañares,
• Marcos Pita,
• Andrea Haase,
• Andreas Luch and
• Andreas Taubert

Beilstein J. Nanotechnol. 2017, 8, 627–635, doi:10.3762/bjnano.8.67

• , δ(CO)), 659 (sh, δ(CO)), 613 (m, scissoring NO2), 569 (vw, CN in plane bending), 523 (w, δ(OCC)), 504 (sh, 1,4-disubstituted aromatic ring bending), 396 (vw, δ(CCN), 347 (vw, δ(COC), δ(OCC)), 311 (vw, possibly due to general skeletal vibrations). Cleavage experiments For evaluating the cleavage of

• to a scissoring NO2 vibration, likely from nitrate anions adsorbed on the SNP surface [47]. It must be noted here that at an excitation wavelength of 514.5 nm, the surface enhancement effect is less pronounced than at other wavelengths, but nevertheless is an established approach [48][49][50][51][52

• negative zeta potential at the beginning of the experiment is due to the presence of residual citrate and nitrate ions adsorbed on the particle surface that are not removed during CBAmPEG@SNP synthesis. This is confirmed by Raman spectroscopy, which detects carboxylate groups (from citrate) and NO2

Gas sensing properties of MWCNT layers electrochemically decorated with Au and Pd nanoparticles

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

Beilstein J. Nanotechnol. 2017, 8, 592–603, doi:10.3762/bjnano.8.64

• their nanometer-sized dimensions and allowing the metal content to be tuned by simply varying the deposition time. The sensing response of unmodified and metal-decorated MWCNTs was evaluated towards different gaseous pollutants (e.g., NO2, H2S, NH3 and C4H10) at a wide range of concentrations in the

• repeatability, and a low detection limit, where all of these sensing properties were controlled by the type and loading of the deposited metal catalytic NPs. Specifically, in the NO2 gas sensing experiments, MWCNTs decorated with the lowest Au content revealed the highest sensitivity at 150 °C, while MWCNTs

• of emissions of toxic, pollutant gases (e.g., NO2, H2S, NH3, C4H10) and greenhouse gases into the atmosphere [1]. The effect of high concentration levels of these gaseous pollutants causes both environmental problems and health consequences for humans (e.g., respiratory and cardiovascular illness

Graphene functionalised by laser-ablated V₂O₅ for a highly sensitive NH₃ sensor

• Margus Kodu,
• Artjom Berholts,
• Tauno Kahro,
• Mati Kook,
• Peeter Ritslaid,
• Helina Seemen,
• Tea Avarmaa,
• Harry Alles and
• Raivo Jaaniso

Beilstein J. Nanotechnol. 2017, 8, 571–578, doi:10.3762/bjnano.8.61

• monolayer per laser pulse are the advantages worth mentioning. The method of PLD has recently been applied to improve the nitrogen dioxide (NO2) sensing properties of chemical vapour deposition (CVD) grown, single-layer graphene in our previous work, using ZrO2 and Ag for functionalisation [14]. In the

• structures was investigated using Raman spectroscopy. Based on the electrical conductivity modulation, the room temperature gas sensing properties of the manufactured sensor structure towards ammonia (NH3) and (for comparison) nitrogen dioxide (NO2) gases were investigated. Results Figure 1a shows a typical

• -functionalised graphene sensor to polluting gases NO2 and NH3. All the gas measurements in this work were recorded under continuous excitation with ultraviolet (UV) light (λ = 365 nm) at room temperature (RT). Illumination by UV light can enhance the sensing performance of graphene-based gas sensors. An

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

• , causing changes in the surface potential and resistivity of the sensing material. The electrical resistance can increase or decrease, depending on the type of doping of MOx (p- or n-type) and on the analyte gas. There are oxidizing gases, such as nitrogen oxide (NO2), and ozone (O3), and reducing gases

• interfering gaseous pollutants (e.g., NO2) revealed that the presence of Pd NPs on the surface of ZnO improves the selectivity in the detection of specific gaseous molecules. Specifically Pd@ZnO chemiresistors showed a high selectivity towards HCs compared to the pristine ZnO-based gas sensors. On the

• contrary, high selectivity towards NO2 gas detection was obtained by using pristine ZnO chemiresistors. Experimental Sol–gel synthesis of ZnO ZnO nanostructures were prepared via a sol–gel process following the procedure reported in [45]. The subsequent washing of the obtained gel led to the complete

Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• as H2 [7], NO2 [8], NOx [9], CO [10], NH3 [11], H2S [12], and VOCs (i.e., methanol, ethanol, propanol [13], and acetone [14]). The influence of effective surface area on the gas sensing properties of TiO2 thin films is also frequently observed and investigated [15]. TiO2 is a wide-band gap

• -made mass flow and humidity controllers. The sensors were exposed to the following gases: acetone (CO(CH3)2, up to 8 ppm), nitric oxides (NOx, up to 400 ppm), hydrogen (H2, up to 2000 ppm), ozone (O3, made by a custom UV generator, up to 500 ppb), and nitrogen dioxide (NO2, up to 100 ppm). Additionally

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra

• Oriol Gonzalez,
• Sergio Roso,
• Xavier Vilanova and
• Eduard Llobet

Beilstein J. Nanotechnol. 2016, 7, 1507–1518, doi:10.3762/bjnano.7.144

• been found to be highly sensitive to nitrogen dioxide levels in air [6][7] and there are commercially available metal oxide NO2 sensors [8]. In particular, many authors have reported nanostructured indium oxide as a promising material for the sensitive detection of nitrogen dioxide at trace levels in

A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors

• Vardan Galstyan,
• Elisabetta Comini,
• Iskandar Kholmanov,
• Andrea Ponzoni,
• Veronica Sberveglieri,
• Nicola Poli,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2016, 7, 1421–1427, doi:10.3762/bjnano.7.133

• materials make them a suitable candidate for various applications [20][21]. Recently we have shown that the functionalization of ZnO with reduced graphene oxide (RGO) sheets improved its sensing performance for NO2 and H2 [22]. Abideen et al. also improved the response of ZnO towards H2 preparing ZnO

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

• ] and WO3 [12] have been reported. Indium oxide (In2O3) is an n-type semiconductor with a band gap of approximately 3.55–3.75 eV, which has been widely used due to its excellent electrical and optical properties. In2O3 also exhibits sensitivity to various vapors and gases, such as NO2 [13], CO [14], H2

NO gas sensing at room temperature using single titanium oxide nanodot sensors created by atomic force microscopy nanolithography

• Li-Yang Hong and
• Heh-Nan Lin

Beilstein J. Nanotechnol. 2016, 7, 1044–1051, doi:10.3762/bjnano.7.97

• fabrication of titanium oxide nanowire (NW) gas sensors [25][26]. NO gas sensing at low concentrations is beneficial for human health [1][2] and environmental monitoring [3]. Various types of metal oxide nanomaterials have been utilized for NO or NO2 gas sensing, e.g., SnO2 [12][15][16][17], ZnO [13][14][17

• the current response. (The current response is shown in Figure S4 in Supporting Information File 1.) It is therefore reasonable to expect that the present sensing results will not change in a high-pressure N2 environment. Possible mechanisms for NO or NO2 sensing by using semiconducting metal oxide

• photoinduced ions are finally removed by pumping as shown in Figure 7g. Table 2 shows a comparison of sensing performances of NO or NO2 metal oxide sensors operated in the photo-activation mode at room temperature reported in the literature. Although not better, the performance of sensor A compares reasonably

Rigid multipodal platforms for metal surfaces

• Michal Valášek,
• Marcin Lindner and
• Marcel Mayor

Beilstein J. Nanotechnol. 2016, 7, 374–405, doi:10.3762/bjnano.7.34

• ], selenols (–SeH) [36][37][38][39], fullerenes [40][41][42], isocyanides (–NC) [30][43][44], nitriles (–CN) [45][46], nitro (–NO2) [46], isothiocyanides (–NCS) [47], methyl sulfide (–SCH3) [31], dithiocarbamates (–NCS2) [48], carbodithiolates (–CS2H) [49][50], hydroxyl (–OH) [51], N-heterocyclic carbenes [52

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

• , respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the

• gas-sensing properties. Keywords: Au-doped ZnO; chemiresistive gas sensor; electrosynthesis; NO2 gas sensor; ZnO nanostructures; Introduction Today the use of low-cost portable gas sensors is essential to detect and to monitor toxic, polluting and combustible gases for the environmental protection

• investigate the influence of ZnO morphology and of Au-doping on the gas-sensing capabilities, taking into the account the importance of the annealing temperature in defining the morphology and the chemical composition. It was found that the NO2 responses of un-doped and Au-doped spherical-like ZnO

Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles

• Dulce G. Romero-Urbina,
• Humberto H. Lara,
• J. Jesús Velázquez-Salazar,
• M. Josefina Arellano-Jiménez,
• Eduardo Larios,
• Anand Srinivasan,
• Jose L. Lopez-Ribot and
• Miguel José Yacamán

Beilstein J. Nanotechnol. 2015, 6, 2396–2405, doi:10.3762/bjnano.6.246

• film for further analysis. The use of microwaves to synthesize silver nanoparticles has been shown to work in the presence of an eco-friendly reducing agent [54]. Silver nitrate can decompose into metallic silver, NO2 gas and O2 by the addition of heat as represented in Equation 1 [55]: In our study

Pt- and Pd-decorated MWCNTs for vapour and gas detection at room temperature

• Hamdi Baccar,
• Atef Thamri,
• Pierrick Clément,
• Eduard Llobet and
• Adnane Abdelghani

Beilstein J. Nanotechnol. 2015, 6, 919–927, doi:10.3762/bjnano.6.95

• -treated carbon nanotubes with Au or Ag using an evaporation technique for NO2 detection at room temperature [29]; however, their sensors were not fully reversible. Penza and co-workers decorated CVD grown carbon nanotubes with Au, Pt or Pd by using sputtering to enhance sensor response towards NO2 and NH3

• -coated carbon nanotubes for discriminating NO2, HCN, HCl, Cl2, acetone and benzene [33]. The sensors from these two groups showed low sensitivity [32][33] at concentrations three orders of magnitude higher than those required for environmental protection applications. Leghrib and co-workers introduced

• non-aromatic (ethanol, methanol and acetone) VOCs together with the response to a pollutant gas (NO2) have been investigated. Experimental Carbon nanotube synthesis, functionalisation and metal decoration The carbon nanotubes used in the experiment were purchased from Nanocyl s.a. (Belgium). They were

Gas sensing properties of nanocrystalline diamond at room temperature

• Marina Davydova,
• Pavel Kulha,
• Alexandr Laposa,
• Karel Hruska,
• Pavel Demo and
• Alexander Kromka

Beilstein J. Nanotechnol. 2014, 5, 2339–2345, doi:10.3762/bjnano.5.243

• -terminated NCD to NO2 and NH3 gases [1]. In their setup, the IDE electrodes were deposited on the top of the monocrystalline diamond. A high concentration of H3O+ ions was observed after exposure of the H-terminated diamond surface to NO2 gas because the electrons were transferred from the diamond sub

Advances in NO₂ sensing with individual single-walled carbon nanotube transistors

• Kiran Chikkadi,
• Matthias Muoth,
• Cosmin Roman,
• Miroslav Haluska and
• Christofer Hierold

Beilstein J. Nanotechnol. 2014, 5, 2179–2191, doi:10.3762/bjnano.5.227

• exciting prospect for carbon nanotubes is in the field of chemical sensing. First reports of the sensitivity of the electrical characteristics of carbon nanotubes to adsorbed gases were reported by Kong et al. [7] and Collins et al. [8] in 2000. Kong et al. showed that gases such as NO2 and NH3 caused a

• nanotube lattice is held together by strong sp2 C–C bonds, which provide the necessary chemical stability to the carbon nanotube. The sensitivity of SWNTs towards NO2 at ambient temperatures, as reported by Kong et al. [7] is particularly interesting. NO2 is a well-known toxic gas and air pollutant and

• monitoring its concentration is crucial for applications such as air quality monitoring. Leveraging the NO2 sensitivity of carbon nanotubes to build highly sensitive, low-power gas sensors is therefore not only of academic, but also of great commercial interest. As such, we will focus on the NO2-SWNT system

Cathode lens spectromicroscopy: methodology and applications

• T. O. Menteş,
• G. Zamborlini,
• A. Sala and
• A. Locatelli

Beilstein J. Nanotechnol. 2014, 5, 1873–1886, doi:10.3762/bjnano.5.198

• . In the above example of FeOx growth on Ru(0001), further oxidation by using NO2 as atomic oxygen source resulted in the transformation of the FeO wetting layer to hematite (α-Fe2O3) and the triangular Fe3O4 islands to maghemite (γ-Fe2O3) [71]. In an independent study, the real-time observation of

Electronic and electrochemical doping of graphene by surface adsorbates

• Hugo Pinto and
• Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

• instance, the exposure of hydrogenated diamond to a humid atmosphere results in p-type doping [46][47], which can be suppressed by NH3 and enhanced by NO2 [48]. Similar effects were reported for carbon nanotubes [49][50]. It would be interesting to see whether they could apply to graphite or indeed if some

Room temperature, ppb-level NO₂ gas sensing of multiple-networked ZnSe nanowire sensors under UV illumination

• Sunghoon Park,
• Soohyun Kim,
• Wan In Lee,
• Kyoung-Kook Kim and
• Chongmu Lee

Beilstein J. Nanotechnol. 2014, 5, 1836–1841, doi:10.3762/bjnano.5.194

• temperatures. In this study, ZnSe nanowires were synthesized by the thermal evaporation of ZnSe powders and the sensing performance of multiple-networked ZnSe nanowire sensors toward NO2 gas was examined. The results showed that ZnSe might be a promising gas sensor material if it is used at room temperature

• . The response of the ZnSe nanowires to 50 ppb–5 ppm NO2 at room temperature under dark and UV illumination conditions were 101–102% and 113–234%, respectively. The responses of the ZnSe nanowires to 5 ppm NO2 increased from 102 to 234% with increasing UV illumination intensity from 0 to 1.2 mW/cm2. The

• response of the ZnSe nanowires was stronger than or comparable to that of typical metal oxide semiconductors reported in the literature, which require higher NO2 concentrations and operate at higher temperatures. The origin of the enhanced response of the ZnSe nanowires towards NO2 under UV illumination is

Highly NO₂ sensitive caesium doped graphene oxide conductometric sensors

• Carlo Piloto,
• Marco Notarianni,
• Mahnaz Shafiei,
• Elena Taran,
• Dilini Galpaya,
• Cheng Yan and
• Nunzio Motta

Beilstein J. Nanotechnol. 2014, 5, 1073–1081, doi:10.3762/bjnano.5.120

• Institute for Bioengineering and Nanotechnology, Australian National Fabrication Facility - QLD Node, Brisbane, QLD 4072, Australia 10.3762/bjnano.5.120 Abstract Here we report on the synthesis of caesium doped graphene oxide (GO-Cs) and its application to the development of a novel NO2 gas sensor. The GO

• , synthesized by oxidation of graphite through chemical treatment, was doped with Cs by thermal solid-state reaction. The samples, dispersed in DI water by sonication, have been drop-casted on standard interdigitated Pt electrodes. The response of both pristine and Cs doped GO to NO2 at room temperature is

• studied by varying the gas concentration. The developed GO-Cs sensor shows a higher response to NO2 than the pristine GO based sensor due to the oxygen functional groups. The detection limit measured with GO-Cs sensor is ≈90 ppb. Keywords: caesium; conductometric; doping; drop casting; gas sensor