Room-Temperature Hydrogen Sensors Based on an In[sup 3+]-Doped SnP[sub 2]O[sub 7] Proton Conductor

Abstract

A potentiometric solid-state gas sensor was fabricated using a proton-conducting Sn 0.9 In 0.1 P 2 O 7 electrolyte with an active Pt/C working electrode in order to study its sensing properties for small quantities ͑100 ppm 3%͒ of H 2 in air at room temperature. The sensor showed electromotive force ͑emf͒ response in the negative direction to changes in the H 2 concentration. Furthermore, the emf value varied linearly with the logarithm of the H 2 concentration, while it was minimally affected by the water-vapor concentration. The sensing mechanism was shown to be based on the mixed potential at the working electrode through measurements of the polarization curves of H 2 and air. The Sn 0.9 In 0.1 P 2 O 7 electrolyte was also applied in two single-chamber H 2 sensors, wherein Pt/C and carbon were used as active and inactive electrodes, respectively; these electrodes were attached on the opposite surfaces or on the same surface of the electrolyte. Both single-chamber sensors could exhibit comparable H 2 sensitivities, compared to the dual-chamber sensor.

Single-Chamber Solid Oxide Fuel Cell Technology—From Its Origins to Today’s State of the Art

“…Anode and cathode strips can also be arranged in an alternating fashion on the same side of the electrolyte to form coplanar electrode arrays [172] or interdigitated, comblike electrode patterns [173,174] to increase the effective electrode area (see Figure 8). Strip or interdigitated electrode configurations are also used in sensor technology [45,175] and in addition to SOFCs, the strip cell design was proposed for MR-DMFCs [22]. A new design approach with polygonal or circular shaped electrodes arranged alternately on the electrolyte surface was patented in [176] and arbitrarily shaped electrode structures were reported in [177].…”

“…Without the need for reactant gas separation, SC-SOFCs could work as gas, temperature or pressure sensors [123,175] in mixed gas conditions or in harsh industrial environments where gas mixtures at elevated temperatures are present. They could be placed as-fabricated inside gas tubes or chimneys by exposing the electrodes directly to the gas mixtures without any need for packaging design.…”

“…The difference in catalytic activity between anode and cathode for the fuel can be used in sensor technology for the detection of fuel gas in gas streams, gas mixtures or air as well as the control of fuel concentrations [123,175]. In a combined fuel cell-sensor system the fuel cell could deliver electrical power to adjust fuel fluctuations detected by the sensor part [123].…”

“…Tomita et al presented a H 2 -gas sensor operating in the single-chamber mode at a temperature of 30 °C [175]. Cells were fabricated from a proton-conducting Sn 0.9 In 0.1 P 2 O 7 electrolyte and Pt/C and C electrodes.…”

Single‐Chamber Fuel Cells

“…Within this scope, SC-SOFCs are considered as gas, temperature, or pressure sensors under mixed gas conditions [88]. Through the hydrocarbon conversion, electrical power and chemicals could be cogenerated [50].…”