H2S Sensing by Hybrids Based on Nanocrystalline SnO2 Functionalized with Cu(II) Organometallic Complexes: The Role of the Ligand Platform

Nitric oxide (NO) is one of the main environmental pollutants and one of the biomarkers noninvasive diagnosis of respiratory diseases. Organic-inorganic hybrids based on heterocyclic Ru (II) complex and nanocrystalline semiconductor oxides SnO 2 and In 2 O 3 were studied as sensitive materials for NO detection at room temperature under periodic blue light (λ max = 470 nm) illumination. The semiconductor matrixes were obtained by chemical precipitation with subsequent thermal annealing and characterized by XRD, Raman spectroscopy, and single-point BET methods. The heterocyclic Ru (II) complex was synthesized for the first time and characterized by 1 H NMR, 13 C NMR, MALDI-TOF mass spectrometry and elemental analysis. The HOMO and LUMO energies of the Ru (II) complex are calculated from cyclic voltammetry data. The thermal stability of hybrids was investigated by thermogravimetric analysis (TGA)-MS analysis. The optical properties of Ru (II) complex, nanocrystalline oxides and hybrids were studied by UV-Vis spectroscopy in transmission and diffuse reflectance modes. DRIFT spectroscopy was performed to investigate the interaction between NO and the surface of the synthesized materials. Sensor measurements demonstrate that hybrid materials are able to detect NO at room temperature in the concentration range of 0.25-4.0 ppm with the detection limit of 69-88 ppb.Nanomaterials 2020, 10, 70 2 of 22 in noninvasive diagnosis of respiratory diseases [7][8][9]. In this case, the limitation of the quantitative determination of NO in exhaled air is due to the low level of its concentration (20-200 ppb) among a wide range of interfering gases [10].Direct determination of nitrogen monoxide in the gas phase is possible using conductometric gas sensors based on various semiconductor metal oxides [7,[10][11][12][13][14][15][16][17][18][19][20][21][22]. To increase selectivity of such analysis along with lower power consumption, complete or partial replacement of thermal heating with photoactivation is a promising approach. Activation of the sensor response under illumination occurs through various mechanisms depending on the nature of the target gas. For oxidizing gases (NO 2 , O 3 ), which compete with oxygen for the same adsorption sites, photogeneration of electron-hole pairs plays a major role in the photodesorption process. On the contrary, for the detection of reducing gases (CO, NH 3 , H 2 S), the presence of chemisorbed oxygen on the surface of the semiconductor oxide is necessary. In this case, the increase in the sensor response under illumination is due to the unpinning of Fermi level of the semiconductor. In most works NO is detected as oxidizing gas. The similar routes of NO and NO 2 sensing was recently evidenced by in situ DRIFT spectroscopy [23]. Our previous works show that highly selective NO 2 detection is possible using visible light photoactivation [24][25][26][27]. To shift the optical sensitivity of semiconductor oxides into the visible range, it is necessary to create defects in the semiconductor matrix or i...

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“…The energies of HOMO and LUMO of RuITP complex were calculated using the methodology described in [34] by the following equations:…”

Section: Materials Characterizationmentioning

confidence: 99%

Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

et al. 2019

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“…The HOMO and LUMO energies of the Ru-TT complex were calculated using the methodology described in [ 71 ], using the following equations: E HOMO = −4.73 − E onset (Ox); E LUMO = −4.73 − E onset (Red) …”

Section: Methodsmentioning

confidence: 99%

Photosensitive Organic-Inorganic Hybrid Materials for Room Temperature Gas Sensor Applications

et al. 2018

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In this work, the hybrids based on nanocrystalline SnO2 or In2O3 semiconductor matrixes and heterocyclic Ru(II) complex are studied as materials for gas sensors operating at room temperature under photoactivation with visible light. Nanocrystalline semiconductor oxides are obtained by chemical precipitation with subsequent thermal annealing and characterized by XRD, SEM and single-point BET methods. The heterocyclic Ru(II) complex is synthesized for the first time and investigated by 1H NMR, 13C NMR APT, MALDI-MS analysis, and UV-Vis spectroscopy. The HOMO and LUMO energies of the Ru(II) complex are calculated from cyclic voltammetry data. The hybrid materials are characterized by TGA-MS analysis and EDX mapping. The optical properties of hybrids are studied by UV-Vis spectroscopy in the diffuse reflection mode. The investigation of spectral dependencies of photoconductivity of hybrid samples demonstrates that the role of organic dye consists in shifting the photosensitivity range towards longer wavelengths. Sensor measurements demonstrate that hybrid materials are able to detect NO2 in the concentration range of 0.25–2 ppm without the use of thermal heating under periodic illumination with even low-energy long-wavelength (red) light.

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“…Moreover, they may improve the adsorption of analyte molecules and form specific complexes [25]. The use of copper and silver as central cation can increase selective interaction with H 2 S, since these elements have a high affinity for sulfur, which can lead to significant decrease of the operating temperature [26,27].…”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

et al. 2021

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This paper presents a comparative analysis of H2S sensor properties of nanocrystalline SnO2 modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO2 and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H2S demonstrated high sensitivity, selectivity toward other reducing gases (H2 (20 ppm), NH3 (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H2S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12–2.00 ppm H2S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H2S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO2/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO2/AgL1 and SnO2/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO2 and Ag(I) organic complexes can enhance the selective detection of H2S.

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H2S Sensing by Hybrids Based on Nanocrystalline SnO2 Functionalized with Cu(II) Organometallic Complexes: The Role of the Ligand Platform

Cited by 7 publications

References 55 publications

Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

Organic-Inorganic Hybrid Materials for Room Temperature Light-Activated Sub-ppm NO Detection

Photosensitive Organic-Inorganic Hybrid Materials for Room Temperature Gas Sensor Applications

Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

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