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Metal-Oxide Based Ammonia Gas Sensors: A Review



This review paper encompasses a study of metal-oxide and their composite based gas
sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging
choice in the gas sensor industry. This review paper focuses on the ammonia sensing
principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity
of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects
and doping by metal or other metal oxides, which will change the microstructure and morphology
of the metal oxides. Different parameters that affect the performances like sensitivity, stability and
selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides
with strengths and limitations in ammonia gas sensing applications are reviewed. The challenges for
the development of high sensitive and selective ammonia gas sensors are also discussed.
