Hydrogen gas sensor utilizing a high proton affinity of 1, 4-diketo-3, 6-bis-(4'-pyridyl)-pyrrolo-[3, 4-c]-pyrrole known as a red pigment has been reviewed. The present sensor is derived from an originally proton sensor (
i.e. acid sensor) based upon the proton acceptor of the pyridyl ring in view of the advent of the fuel cell in the near future. Special attention has been paid to the correlation between H
2 sensitivity and crystal structure. The sensor is characterized by a high H
2 sensitivity, reversible operation at room temperature and scarcely influenced by ambient gases, such as CO, CO
2, NO, CH
4, SO
2, CH
3OH, C
2H
5 OH as well as water moisture. Similar H
2 sensors based upon dipyridylperylene-imides or tetrapyridylcopperphthalocyanine have also been presented.
View full abstract