Gas Polarographic Oxygen Sensor Using the Pores of the Pt Cathode as a Gas Diffusion Barrier

Abstract

A gas polarographic oxygen sensor using the pores of the Pt cathode as an oxygen diffusion barrier has been investigated in O2–N2 gas mixtures at 600°C. As expected, the pores of the cathode functioned as a gas diffusion barrier restricting the access of gaseous oxygen to the interface of the Pt cathode and a zirconia electrolyte; consequently, the limiting current was realized. The resulting current increased linearly with the oxygen concentration in the range of 3–25% in the ambient atmosphere when the voltage applied to the cell was held constant within a range of 0.6–2.4 V. In addition, the output current of the sensor was interpreted to be a mixed current of both an ohmic current proportional to the applied voltage and a current based on the diffusion restriction of gaseous oxygen.

Humidity‐Sensing Characteristics in Wet Air of a Gas Polarographic Oxygen Sensor Using a Zirconia Electrolyte

“…As can be seen from Eq. [5] and [6], the limiting current is virtually independent of the total pressure (3,4). Since Xoz = 0,21 in dry air in Eq.…”

“…Recently, gas polarographic oxygen sensors using an electrochemical oxygen pump with a zirconia electrolyte have been extensively investigated (1)(2)(3)(4)(5)(6)(7). This type of oxygen sensor shows the reproducible limiting current plateau (saturated current plateau against the applied voltage) due to the oxygen diffusion overpotential at the cathode with an artificial technique.…”

Study of YSZ Amperometric Oxygen Sensor with a Dense Barrier Layer

“…lean-burn combustion. A new type of amperometric oxygen sensor has been expected for the lean-burn combustion, because of its wide linear dependence of oxygen gas [1][2][3][4][5][6][7][8]. The amperometric oxygen sensor comprises a diffusion barrier and an oxygen pump assembled by the anode, the YSZ electrolyte and the cathode.…”

Characterization of Yttria-Stabilized Zirconia Thin Films Prepared by Radio Frequency Magnetron Sputtering for a Combustion Control Oxygen Sensor

“…Yttria-stabilized zirconia, a well known oxygen ion conductor, is one of the many solid-state ionic materials utilized in the variety of electrochemical devices including fuel cells, oxygen pumps, and chemical gas sensors because of a number of superior properties such as heat resistance, high hardness, chemical durability, and high oxygen ionic conductivity. 1,2 It is also used as a buffer layer to deposit thin films of high-temperature superconductors on the substrates such as silicon, alumina, and sapphire. Bulk-type YSZ oxygen sensors especially have been widely used for combustion control in heat-treatment furnaces, glass tank furnaces, ceramic kilns, boilers, and gas stoves and also for oxygen control in steel and copper melts.…”

“…However, thin-film sensors would show comparable gas sensing characteristics at lower temperatures than bulk sen-sors due to the decrease in ohmic resistance of the solid electrolyte with decreasing the thickness. [9][10][11] YSZ thin films have been deposited for thin-film fuel cells by a number of techniques such as sol-gel, spray pyrolysis, evaporation, chemical vapor deposition (CVD), and radio frequency (rf) sputtering. [12][13][14][15][16][17][18] Among these techniques, the rf magnetron reactive sputtering technique offers better stoichiometry of the film in addition to the advantage of controlling oxygen atomic percent in YSZ thin films.…”