Nanocrystalline Metal Oxides for Methane Sensors: Role of Noble Metals

Abstract

Methane is an important gas for domestic and industrial applications and its source is mainly coalmines. Since methane is extremely inflammable in the coalmine atmosphere, it is essential to develop a reliable and relatively inexpensive chemical gas sensor to detect this inflammable gas below its explosion amount in air. The metal oxides have been proved to be potential materials for the development of commercial gas sensors. The functional properties of the metal oxide-based gas sensors can be improved not only by tailoring the crystal size of metal oxides but also by incorporating the noble metal catalyst on nanocrystalline metal oxide matrix. It was observed that the surface modification of nanocrystalline metal oxide thin films by noble metal sensitizers and the use of a noble metal catalytic contact as electrode reduce the operating temperatures appreciably and improve the sensing properties. This review article concentrates on the nanocrystalline metal oxide methane sensors and the role of noble metals on the sensing properties.

The Effect of Catalytic Metal Contact on Methane Sensing Performance of Nanoporous ZnO -Si Heterojunction

“…FESEM images suggest the particle size of the ZnO to be ~40-50 nm whereas EDX indicate the overall presence of (by weight) 74. and also retard the phase transition due to the formation of Pd-H, Pd-Ag alloy is preferred as contact material in sensor applications. [24,25]. showing band bending upon exposure to methane ψ MA , ψ MG are the work function of M in air (in pure N2 in our case) and in gas respectively.…”

“…The variation of the saturation current and ideality factor with operating temperature and variation of barrier height with the methane concentration are shown in Figure ( S1 without gas S1 with gas S2 without gas S2 with gas S3 without gas S3 with gas S1 with gas S1 without gas S2 with gas S2 without gas S3 with gas S3 without gas Fig 8 (b) can be attributed to the instabilities provided by the interfacial dipole layer created due to the H diffusion through the Pd-Ag, which makes the behavior of the curves for S1 and S2 quite different from S3 in which no Pd-Ag contact is involved [24,27]. These factors also influence the variation in saturation current.…”

Analysis and Design of an Effective Light Interference Methane Sensor Based on Three-Dimensional Optical Path Model

“…The thermal conductivity methane sensor makes use of the difference in thermal conductivity between methane and air to obtain the electrical signals [4,5]. The detection principle of gas sensitive methane sensor is that the resistivity of metal oxide changes significantly when the metal oxide is adsorbed on different gases [6][7][8]. The principle of infrared methane sensor is that different gases have different absorption spectra of infrared radiation, and the intensity of absorption is related to the methane concentration [9][10][11].…”

Fabrication and characterization of nanostructured (Sn–Ti)O2 pellets and films for liquefied petroleum gas sensing

“…Gas sensors using metal oxide semiconductors are the fundamentals of smart device as both the structure and morphology of these materials can be controlled precisely and so they are referred to as a functional oxides. The structures of functional oxides are very diverse and varied, and there are infinite new phenomena and applications [11][12][13][14][15][16]. They have been researched for several decades owing to their advantage such as low cost fabrication, the high sensitivity and possibility of miniaturization.…”