Semiconductor Metal Oxides as Hydrogen Gas Sensors

Hydrogen (H2) is a clean, portable and potentially inexhaustible energy source with the potential to become a panacea for clean energy generation. However, H2 has wide explosive concentration range (4–75 vol%), low ignition energy (0.02 mJ) and large flame propagation velocity. Due to its ultra small molecular size, confinement and containment of this gas are difficult. Moreover, H2 cannot be detected by human senses because it is colorless and odorless. Thus, accurate detection and monitoring of hydrogen is an important issue. This presentation is a review of hydrogen gas sensors based on semiconductor metal oxides synthesized by a variety of synthetic techniques, namely RF magnetron sputtering, reactive RF sputtering, electro-spinning, Flame spray pyrolysis, hydrothermal and precipitation. The effect of synthetic methods and metal loading on the metal oxides on the response of hydrogen sensors will be discussed.