Editors’ Choice—Review—Solid-State Electrochemical Carbon Dioxide Sensors: Fundamentals, Materials and Applications

Abstract

The recent series of global catastrophic events (e.g., heatwaves, flooding) have again raised the concerns over the greater impact of climate change. The focus has been concentrated towards reducing CO2 emissions from fossil fuel based energy systems. It is necessary to build a commercially viable CO2 sensor with high reliability. The gas-sensing field has shifted from using a cumbersome gas-reference electrode to solid-state electrochemical devices because they can be employed to detect CO2 in real-time overcoming the limits of widely used IR-based CO2 sensors. Here, solid electrolytes and mixed conducting semiconductor-based gas sensors for various gaseous species including CO2 are reviewed. The study on semiconducting metal oxides (SMOs) has been pushed forward as a most viable option for commercializing monolithic all-solid-state electrochemical gas sensors. Among SMOs, the perovskite-type metal oxides are considered as one of the promising structures for next-generation greenhouse gas sensors due to their remarkable thermal and chemical stability. This article also includes the fundamental understanding of essential factors that govern the electrical signals in all-solid-state electrochemical gas sensors.

A Robust Miniaturized Gas Sensor for H2 and CO2 Detection Based on the 3ω Method

“…where I is the RMS value of the current applied to the sensor, R the resistance of the sensor measured at room temperature, and α the temperature coefficient of resistance of the heating element, which was obtained in experiments as 4.1 × 10 −3 K −1 . The analytical data were obtained for different frequencies using Equation (6). Based on a wire diameter of 8 µm and a winding radius of 50 µm, the thermal quantities ρ and c p were calculated in proportion from tungsten and air.…”

“…Table 1. Thermal and electrical values used for the analytical calculations using Equation (6). The electrical parameters I eff and R were taken from the simulation, and the thermal quantities ρ and c p were calculated proportionally for tungsten and air using literature values.…”

“…Due to the thermal capacitance, respectively the low-pass behaviour of the sensor element, the amplitude of the temperature oscillations ∆T AC experiences an attenuation at higher frequencies. The RMS values of these amplitudes ∆T AC for different frequencies are compared to the results of the analytical model (see Equation (6)) and the experimental data in Section 5. The DC-component of the heater temperature T DC is constant, whereas the amplitudes of the temperature oscillation T AC depend on the frequency.…”

“…In terms of hydrogen gas sensors, Huebert et al provide a good comparison of different operating principles [2]. Metal oxide [3,4] and electrochemical sensors [5,6] are the most common types of gas sensors. Both are able to resolve very low gas concentrations and can therefore be used for the detection of gas traces.…”

Light-activated gas sensing: a perspective of integration with micro-LEDs and plasmonic nanoparticles

“…The gas sensors in IoE application are required to have a small size with low power consumption for their embedding in portable devices, not to mention excellent gas sensing performance. 2 To achieve the requirements for IoE application, various gas sensor principles have been suggested including cantileverbased gas sensors 3 , capacitive gas sensors 4 , thermometric gas sensors 5 , optical gas sensors 6 , field-effect transistor gas sensors 7 , colorimetric gas sensors 8 , solid-state electrochemical gas sensors [9][10] , or chemoresistive gas sensors [11][12][13] . Among them, the chemoresistive gas sensors have been considered the most appropriate principle due to their simple structures with easy fabrication processes and low cost.…”