Abstract: The search for new materials to create active layers of sensors for the detection of toxicants in water and air is an urgent task. Metal phthalocyanine (MPc) films are widely studied as active layers of chemiresistive sensors for determining low concentrations of various gases (e.g. NH3, H2S, NOx). Alternatively, chemiresistive sensors based on hybrid materials are also used. The interest in hybrid materials is due to the synergistic effect that occurs when combining the properties of two or more chemical compounds forming a hybrid material. Thus, it was shown in a number of papers that the use of semiconductor films modified with noble metal nanoparticles as active layers of chemiresistive sensors leads to an increase in their sensitivity several times. In this contribution, we summarize the results obtained by our research group in the field of applications of metal phthalocyanines (MPc and MPcFx, M = Cu, Co, Zn, VO; x = 0, 4, 16) and their hybrids with noble metal nanoparticles (MNP, M = Au, Ir) as active layers of chemiresistive gas sensors, with a primary focus on the sensors for NH3 and NO detection. Attention is paid to the study of new hybrid structures "MNP/phthalocyanine" obtained by gas-phase deposition methods. MPc films were prepared by physical vapor deposition, while MNPs were deposited by a metal–organic chemical vapor deposition (MOCVD) method. The dependence of the sensor characteristics of hybrid film structures on their composition and structural features (molecular structure of phthalocyanine, concentration and size of nanoparticles) has been studied. It was shown that the modification of MPc films with nanoparticles improved the sensor performance and the obtained hybrid structures could be used for selective detection of low (ppb-level) concentrations of NH3 and NO in the presence of some reducing gases and volatile organic compounds, viz. carbon dioxide, acetone, dichloromethane, ethanol, and even at high humidity. The response of Au/CoPc heterostructures to NH3 and NO gases increased with an increase in the concentration of gold. The sensor response of Au/CoPc heterostructures to NH3 increased 2–3.3 times compared to CoPc film, whereas in the case of NO it increased up to 16 times. The detection limits of the Au/CoPc heterostructure with a gold content of ca. 2.1 µg/cm2 for NH3 and NO were 0.1 ppm and 4 ppb, respectively. In the case of Ir/CoPc hybrid structures, the sensor response to NO depended not only on the Ir concentration but also on the condition of the MOCVD process, e.g. the type of the gas-reactant (H2 or O2) and its ratio to the carrier gas (Ar/H2 = 0.5-2). The prepared heterostructures exhibited a limit of NO detection up to 4 ppb.

Cite: Basova T.V. , Klyamer D.D. , Bonegardt D.V. , Dorovskikh S.I.
Chemiresistive Gas Sensors based on Metal Phthalocyanines and Their Hybrid Structures with Metal Nanoparticles
2nd Semiconductor Materials & Device Physics Conference 18-24 Apr 2024