Phthalocyanine based gas sensors

Kanefusa S and Nitta M 1992 The detection of H2 gas by metal phthalocyanine-based gas sensors Sensors Actuators B 9 85-90 Eguchi K, Kayser P, Menil F, Lucat C, Aucouturier J L and Portier J 1990 Detection of phosphine at the ppm level by Sri yCaj,Fe03 thick layers pretreated with highly concentrated phosphine in air. Evidence of a transition of the surface conductivity from p- to n-type Sensors Actuators B 2 193-7 Gerblinger J and Meixner H 1991 Fast oxygen sensors based on sputtered strontium titanate Sensors Actuators B 4 99-102... 

Bouvet, M., Parra, V., Locatelli, C. Xiongb, H. (2009). Electrical transduction in phthalocyanrne-based gas sensors from classical chemiresistors to new functional stmc-tures J. Porphyrins Phthalocyanines, 13, 84-91. 

Quite a few phthalocyanine derivatives have been reported to date with regard to the conductivity in forms of LB films [222-231], some of them aimed at constructing chemical sensors [207,232-234]. Voltage controlled negative resistance [235] as well as electro-chromism [236] have been reported. Porphyrines were also used for the construction of conductive LB films [237,238] and applied to porphyrin based gas sensors [239-241]. 

Bouvet, M., Phthalocyanine-based filed-effect transistors as gas sensors. Anal. Bioanal. Chem., 384, 366, 2006. 

Various types of solid-state NO2 sensors have been proposed based on semiconducting metal oxides (including heterocontact materials) [42-50,58,59,234-238], solid electrolytes [1,239,240], metal phthalocyanine [241], and SAW devices [242]. Among these NO2 sensors, the semiconducting metal oxides and solid electrolytes appear to be the best. Specifically, semiconducting metal oxide gas sensors are most attractive because they are compact, sensitive, of low cost, and have low-power consumption. Their basic mechanism is that the NO2 gas is adsorbed on the surface of the material this decreases the free electron density into the space-charge layer and results in a resistance increase [243]. 

Gu C., Sun L., Zhang T., Li T., and Zhang X., High-sensitivity phthalocyanine LB film gas sensor based on field effect transistors. Thin Solid Films, 327-329, 383-386, 1998. 

Gas sensors based on phthalocyanine and porphyrin films were firstly used to detect the vapors of organic planar compounds with conjugated double bonds, due to then-strong 7T-7T interactions. Table 3.1 provides a list of phthalocyanines and porphyrins used in various sensors for the detection of aromatic compounds. 

Metallophthalocyanines, MPc, are known for their high thermal stability and very low solubility in any solvents. Transition metal-based phthalocyanines have attracted attention in the areas of fuel cells, gas sensors and biosensors . Most of these applications require the use of phthalocyanines in the form of thin films. Further, it is desirable to have ordered, well-packed, and oriented molecular layers of phthalocyanines on various substrates. The metal phthalocyanines constitute an important class of compounds that provide models for theoretical and experimental studies involving electron-mediated processes one of the main areas of interest is the electrocatalytic reduction of oxygen by metal phthalocyanines. ... 

Nieuwenhuizen MS, Harteveld JLN (1994) An automated SAW gas sensor testing system. Sens Actuators A 44 219-229 Oprea A, Weimar U, Simon E, Fleischer M, Frerichs H-P, WUbertz C, Lehmann M (2006) Copper phthalocyanine suspended gate field effect transistors for NOj detection. Sens Actuators B 118 249-254 Ozturk ZZ, Kilinc N, AtillaD, Gurek AG, Ahsen V (2009) Recent studies of chemical sensors based on phthalocytmines. 

Phthalocyanines constitute one group of organic materials with thermal stability >400°C, and they are usually considered to have semiconducting rather than insulating properties. Thin layers of phthalocyanine complexes based on metals like lead [12.5] and copper [126] have been particularly carefully studied as potential gas sensors [127]. The conductance of these films is a very sensitive function of gases with electron-acceptor properties, including nitrogen dioxide, chlorine. 

Bouvet M (2006) Phthalocyanine-based field-effect transistors as gas sensors. Anal Bioanal Chem 384 366-373 Bouvet M, Leroy A, Simon J, Toumilhac F, Guillaud G, Lessnick P, Maillard A, Spirkovitch S, Debliquy M, de Haan A, Decroly A (2001a) Detection and titration of ozone using metaUophthalocyanine based field effect transistors. Sens Actuators B 72 86-93... 

Gas sensor applications of hybrids based on MN4-MC and CNTs have also been described. Liang et al. [55] demonstrated the fabrication and application of 2,9,16,23-tetrakis(2,2,3,3-tetralluoropropoxy) metal(II) phthalocyanines functionalized carbon nanotubes (MWCNTs/TFPMPc, M=Co, Zn, Cu, Pb, Pd, and Ni) for NH3 detection. The self-assembly method based on the jt-jt interactions was used to modify the CNTs, subsequendy deposited on gold interdigitated electrodes by drop-dry technique (Fig. 8a). 

Among the transition metal complexes, phthalocya-nines have been studied extensively due to their exotic properties, e.g. high thermal stability, photo and electrical responses, etc. Consequently, the studies of the application of phthalocyanine based conductive LB films to gas sensors or electrochromism have been carried out by many groups, although the conductivity of the materials is relatively low compared with other conductive LB films. Highly conductive LB films of this class of material have been mainly obtained using metal(dmit)2 salts. 

Electrocatalytic groups such as porphyrins and phthalocyanines that act as supramolecular hosts for different metals and mimic the active sites of various proteins are commonly used in amperometric sensors [66,67]. A biomimetic sensor based on an artificial enzyme or synzyme has been demonstrated [68]. The artificial enzyme used in this study was a synthetic polymer (quaternised polyethyleneimine containing 10% primary amines) which decarboxylated oxaloacetate. The product carbon dioxide was detected potentiometrically via a gas membrane electrode. 

Schollhorn et al. 1998 Ceyhan et al. 2006) (see Table 10.2). For explanation of MPc gas sensitivity the approach based on gas molecule interaction with the Ti-electron network of the phthalocyanines is normally used (Roisin et al. 1992). For example, in the case of VOCs sensors the VOCs would play an electron acceptor role. When the VOC molecules interact with the 7i-electron network of the phthalocyanines, it causes the transfer of an electron from the phthalocyanine ring to the VOC molecule (Schollhorn et al. 1998). Thus, the induced positive holes on the film surface give rise to an increase in the p-type conductivity of the film. 

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