possible for any recognized sensing layer made of inorganic, organic, or hybrid
nanomaterials provided that the layer is interacting with the analyte.
10.4.5 Operating Temperature
The operating temperature is also an important parameter for the air pollution sensor
and it should be room temperature as the best one. Inorganic nanomaterials especially metal oxide layers have been extensively used for this purpose, and some of
those are also commercialized. However, the major drawback with inorganic
nanomaterials is that metal oxide sensors need high operating temperatures for
sensing. Moreover, at high operating temperature, the layer of inorganic
nanomaterials often reacts with the analyte. Here is the advantage of organic
nanomaterials as sensing layer as the interaction of organic nanomaterials-based
sensing layer with chemical analyte is rather strong at room temperature. The hybrid
nanomaterials with inorganic matrices should have high operating temperature as it
is close to matrix materials. In addition, hybrid nanomaterials with organic especially
polymer matrices should have operating temperature at room temperature. For
example, a hydrogen gas sensor array employing vertically aligned titanium dioxide
nanotube was operated at 100
C temperature (Lee et al. 2011a), while both
polyaniline nanofiber (Sadek et al. 2007) and polyaniline–titanium dioxide
nanocomposite (Srivastava et al. 2011) were operated at room temperature.
10.5 Sensing of Air Pollutant by Nanomaterials
As explained earlier, the sensing of gas molecules is important to environmental
monitoring, control of chemical processes, and agricultural and medical applications. In addition, the detection of industrial toxic gases such as carbon monoxide,
oxides of nitrogen, ammonia, hydrocarbons like LPG, and volatile organic compounds is critical for many industries in order to control air pollution. In recent
decades the sensing of gases like carbon dioxide, sulfur dioxide, oxygen, ozone,
hydrogen, moisture, and several organic vapors is important for controlling industrial and vehicle emissions, household security, and environmental monitoring. All
three types of nanomaterials are employed to develop the devices for the successful
sensing of those air pollutants. In this section, the studies on the sensing of main
types of gaseous air pollutants using nanomaterials have been reviewed exclusively.
10.5.1 Oxides of Carbon
The main types of oxides of carbons are carbon monoxide and carbon dioxide. The
carbon dioxide is released as complete combustion product of any types of fuel,
372
P. Kar
nanomaterials provided that the layer is interacting with the analyte.
10.4.5 Operating Temperature
The operating temperature is also an important parameter for the air pollution sensor
and it should be room temperature as the best one. Inorganic nanomaterials especially metal oxide layers have been extensively used for this purpose, and some of
those are also commercialized. However, the major drawback with inorganic
nanomaterials is that metal oxide sensors need high operating temperatures for
sensing. Moreover, at high operating temperature, the layer of inorganic
nanomaterials often reacts with the analyte. Here is the advantage of organic
nanomaterials as sensing layer as the interaction of organic nanomaterials-based
sensing layer with chemical analyte is rather strong at room temperature. The hybrid
nanomaterials with inorganic matrices should have high operating temperature as it
is close to matrix materials. In addition, hybrid nanomaterials with organic especially
polymer matrices should have operating temperature at room temperature. For
example, a hydrogen gas sensor array employing vertically aligned titanium dioxide
nanotube was operated at 100
C temperature (Lee et al. 2011a), while both
polyaniline nanofiber (Sadek et al. 2007) and polyaniline–titanium dioxide
nanocomposite (Srivastava et al. 2011) were operated at room temperature.
10.5 Sensing of Air Pollutant by Nanomaterials
As explained earlier, the sensing of gas molecules is important to environmental
monitoring, control of chemical processes, and agricultural and medical applications. In addition, the detection of industrial toxic gases such as carbon monoxide,
oxides of nitrogen, ammonia, hydrocarbons like LPG, and volatile organic compounds is critical for many industries in order to control air pollution. In recent
decades the sensing of gases like carbon dioxide, sulfur dioxide, oxygen, ozone,
hydrogen, moisture, and several organic vapors is important for controlling industrial and vehicle emissions, household security, and environmental monitoring. All
three types of nanomaterials are employed to develop the devices for the successful
sensing of those air pollutants. In this section, the studies on the sensing of main
types of gaseous air pollutants using nanomaterials have been reviewed exclusively.
10.5.1 Oxides of Carbon
The main types of oxides of carbons are carbon monoxide and carbon dioxide. The
carbon dioxide is released as complete combustion product of any types of fuel,
372
P. Kar