Development of Potentiometric Sensors for C₂H₄ Detection

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Science

Background:

• Vehicle emissions regulations, particularly for hydrocarbons and NOx in diesel engines, are becoming stricter globally.
• Accurate sensing of exhaust components like ethylene (C₂H₄) and carbon monoxide (CO) is crucial for emissions control.
• Developing selective and sensitive gas sensors is essential for meeting these regulatory demands.

Purpose of the Study:

• To screen and identify promising working electrode materials for a potentiometric sensor designed to detect ethylene (C₂H₄) in diesel exhaust.
• To evaluate the sensor's performance, including selectivity and cross-sensitivity, particularly towards carbon monoxide (CO).
• To assess the sensor's response under varying conditions, including the presence of polycyclic aromatic hydrocarbons and humidity.

Main Methods:

• Fabrication of a potentiometric sensor utilizing an 8YSZ electrolyte and platinum reference electrode.
• Screen-printing and testing of various working electrode materials, including Fe₀.₇Cr₁.₃O₃, ZnCr₂O₄, Fe₂NiO₄, La₀.₈Sr₀.₂CrO₃-δ (LSC), La₀.₈Sr₀.₂MnO₃ (LSM), and NiO+5%wt Au.
• Measurement of sensor voltage response to varying concentrations of C₂H₄ and CO at 550 °C.
• Assessment of cross-sensitivity to CO and the impact of phenanthrene and wet conditions on sensor performance.

Main Results:

• Fe₀.₇Cr₁.₃O₃ demonstrated the most promising performance as a working electrode material for C₂H₄ detection.
• The Fe₀.₇Cr₁.₃O₃ sensor exhibited a good response to C₂H₄ with low cross-sensitivity to CO.
• Sensor performance was affected by high concentrations of polycyclic aromatic hydrocarbons (leading to saturation) and wet conditions (reducing C₂H₄ sensitivity and increasing CO cross-sensitivity).

Conclusions:

• Fe₀.₇Cr₁.₃O₃ is a highly promising material for developing potentiometric sensors to detect ethylene in diesel exhaust.
• The sensor shows potential for selective C₂H₄ monitoring, though its performance can be impacted by environmental factors like humidity and high PAH concentrations.
• Further optimization is needed to address limitations related to signal saturation and performance under humid operating conditions.