Self-assembled α-Fe2O3-GO nanocomposites: Studies on physical, magnetic and ammonia sensing properties

An amperometric type sensor whose active layer is derived from a tetra core-substituted organic semiconductor, naphthalene diimide (NDI-CN4), has been evaluated for ammonia gas (3, 6, 25 and 50 ppm)...

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Redox-Active Monolayers Self-Assembled on Gold Electrodes—Effect of Their Structures on Electrochemical Parameters and DNA Sensing Ability

Molecules ◽

10.3390/molecules25030607 ◽

2020 ◽

Vol 25 (3) ◽

pp. 607 ◽

Cited By ~ 1

Author(s):

Kamila Malecka ◽

Shalini Menon ◽

Gopal Palla ◽

Krishnapillai Girish Kumar ◽

Mathias Daniels ◽

...

Keyword(s):

Electron Transfer ◽

Transition Metal ◽

Redox Activity ◽

Gold Electrodes ◽

Complex Structures ◽

Transfer Coefficients ◽

Sensing Properties ◽

Redox Active ◽

Electrochemical Parameters ◽

Self Assembled

The background: The monolayers self-assembled on the gold electrode incorporated transition metal complexes can act both as receptor (“host” molecules) immobilization sites, as well as transducer for interface recognitions of “guest” molecules present in the aqueous solutions. Their electrochemical parameters influencing the sensing properties strongly depend on the transition metal complex structures. The objectives: The electrochemical characterization of the symmetric terpyridine–M2+–terpyridine and asymmetric dipyrromethene–M2+–terpyridine complexes modified with ssDNA probe covalently attached to the gold electrodes and exploring their ssDNA sensing ability were the main aims of the research presented. The methods: Two transition metal cations have been selected: Cu2+ and Co2+ for creation of redox-active monolayers. The electron transfer coefficients indicating the reversibility and electron transfer rate constant measuring kinetic of redox reactions have been determined for all SAMs studied using: Cyclic Voltammetry, Osteryoung Square-Wave Voltammetry, and Differential Pulse Voltammetry. All redox-active platforms have been applied for immobilization of ssDNA probe. Next, their sensing properties towards complementary DNA target have been explored electrochemically. The results: All SAMs studied were stable displaying quasi-reversible redox activity. The linear relationships between cathodic and anodic current vs. san rate were obtained for both symmetric and asymmetric SAMs incorporating Co2+ and Cu2+, indicating that oxidized and reduced redox sites are adsorbed on the electrode surface. The ssDNA sensing ability were observed in the fM concentration range. The low responses towards non-complementary ssDNA sequences provided evidences for sensors good selectivity. The conclusions: All redox-active SAMs modified with a ssDNA probe were suitable for sensing of ssDNA target, with very good sensitivity in fM range and very good selectivity. The detection limits obtained for SAMs incorporating Cu2+, both symmetric and asymmetric, were better in comparison to SAMs incorporating Co2+. Thus, selection of the right transition metal cation has stronger influence on ssDNA sensing ability, than complex structures.

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Morphology-controlled self-assembled micro-structures of nickel porphyrin with enhanced ethanol sensing properties

Inorganic Chemistry Communications ◽

10.1016/j.inoche.2019.03.030 ◽

2019 ◽

Vol 105 ◽

pp. 112-118 ◽

Cited By ~ 1

Author(s):

Pan Ma ◽

Liang Lv ◽

Peihua Zhu ◽

Yucheng Wang ◽

Shanshan Li

Keyword(s):

Sensing Properties ◽

Nickel Porphyrin ◽

Self Assembled ◽

Ethanol Sensing ◽

Micro Structures

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

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.10.58 ◽

2019 ◽

Vol 10 ◽

pp. 565-577 ◽

Cited By ~ 3

Author(s):

Juan Casanova-Cháfer ◽

Carla Bittencourt ◽

Eduard Llobet

Keyword(s):

Carbon Nanotubes ◽

Nitrogen Dioxide ◽

Photoelectron Spectroscopy ◽

Gas Sensing ◽

Carbon Chain ◽

Head Group ◽

Carbon Chain Length ◽

Sensing Properties ◽

Gas Sensing Properties ◽

Self Assembled

Here we describe the development of chemoresistive sensors employing oxygen-plasma-treated, Au-decorated multiwall carbon nanotubes (MWCNTs) functionalized with self-assembled monolayers (SAMs) of thiols. For the first time, the effects of the length of the carbon chain and its hydrophilicity on the gas sensing properties of SAMs formed on carbon nanotubes are studied, and additionally, the gas sensing mechanisms are discussed. Four thiols differing in the length of the carbon chain and in the hydrophobic or hydrophilic nature of the head functional group are studied. Transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy are used to analyze the resulting gas-sensitive hybrid films. Among the different nanomaterials tested, short-chain thiols having a hydrophilic head group, self-assembled onto Au-decorated carbon nanotubes were most responsive to nitrogen dioxide and ethanol vapors, even in the presence of ambient humidity. In particular, this nanomaterial was about eight times more sensitive to nitrogen dioxide than bare Au-decorated carbon nanotubes when operated at room temperature. This response enhancement is attributed to the interaction, via strong hydrogen bonding, of the polar molecules tested to the polar surface of hydrophilic thiols. The approach discussed here could be extended further by combining hydrophilic and hydrophobic thiol SAMs in Au-MWCNT sensor arrays as a helpful strategy for tuning sensor 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.

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Ammonia Sensing Properties of Organic Inks Deposited on Flexible Subtrates

Lecture Notes in Electrical Engineering - Sensors and Microsystems ◽

10.1007/978-90-481-3606-3_36 ◽

2009 ◽

pp. 193-196

Author(s):

A. Arena ◽

N. Donato ◽

G. Saitta ◽

G. Rizzo ◽

G. Neri

Keyword(s):

Sensing Properties ◽

Ammonia Sensing

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Self-Assembled Vanadium Oxide Nanoflakes for p-Type Ammonia Sensors at Room Temperature

Nanomaterials ◽

10.3390/nano9030317 ◽

2019 ◽

Vol 9 (3) ◽

pp. 317 ◽

Cited By ~ 5

Author(s):

Haihong Yin ◽

Changqing Song ◽

Zhiliang Wang ◽

Haibao Shao ◽

Yi Li ◽

...

Keyword(s):

Vanadium Oxide ◽

Room Temperature ◽

Gas Sensing ◽

Electron Microscopies ◽

Ammonia Sensing ◽

Transmission Electron ◽

Order Of Magnitude ◽

Self Assembled ◽

Ammonia Sensors ◽

P Type

VO2(B), VO2(M), and V2O5 are the most famous compounds in the vanadium oxide family. Here, their gas-sensing properties were investigated and compared. VO2(B) nanoflakes were first self-assembled via a hydrothermal method, and then VO2(M) and V2O5 nanoflakes were obtained after a heat-phase transformation in nitrogen and air, respectively. Their microstructures were evaluated using X-ray diffraction and scanning and transmission electron microscopies, respectively. Gas sensing measurements indicated that VO2(M) nanoflakes were gas-insensitive, while both VO2(B) and V2O5 nanoflakes were highly selective to ammonia at room temperature. As ammonia sensors, both VO2(B) and V2O5 nanoflakes showed abnormal p-type sensing characteristics, although vanadium oxides are generally considered as n-type semiconductors. Moreover, V2O5 nanoflakes exhibited superior ammonia sensing performance compared to VO2(B) nanoflakes, with one order of magnitude higher sensitivity, a shorter response time of 14–22 s, and a shorter recovery time of 14–20 s. These characteristics showed the excellent potential of V2O5 nanostructures as ammonia sensors.

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