Acid zirconium phosphates and phosphonates as proton conductors and their use for solid state gas sensors
- Elce di Sotto, Perugia (Italy)
Solid state proton conductors can be employed in several electrochemical devices, among which fuel cells and gas sensors are of particular interest. Microcrystalline {alpha}-layered zirconium phosphate [{alpha}-Zr(HPO){sub 4}){sub 2}{center_dot}H{sub 2}O] is a proton conductor, but its conductivity {sigma} {approx} 10{sup -5} - 10{sup -6}{omega}{sup -1} cm{sup -1} at 20{degrees}C and 90% relative humidity) is too low for practical applications in some electrochemical devices. Conductivity enhancements have been obtained by (1) preparation of membranes made up of highly oriented particles (pellicular zirconium phosphate), (2) intercalation of suitable organic molecules (especially hydrazine and pyrazole), and (3) synthesis of organic derivatives containing acid ionogenic groups in the interlayer region. The best results have been obtained for Zr alkylsulfophenyl phosphonates possessing -SO{sub 3}H in the interlayer region. The highest conductivity is on the order of 10{sup -2}{omega}{sup -1} cm{sup -1} at 100{degrees}C and 60% relative humidity. Pellicular zirconium phosphate has already been used in the development of amperometric and potentiometric solid state sensors for hydrogen, oxygen and carbon monoxide. Noncatalytic metal hybrides such as ZrH{sub x} and TiH{sub x} are very suitable solid reference electrodes for these sensors, since they are non-blocking electrodes for protons, but, at the same time, they are not sensitive to molecular hydrogen.
- OSTI ID:
- 249798
- Journal Information:
- Russian Journal of Electrochemistry, Vol. 29, Issue 12; Other Information: PBD: Dec 1993; TN: Translated from Elektrokhimiya; 29: No. 12, 1433-1441(1993)
- Country of Publication:
- United States
- Language:
- English
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