High-sensitivity mixed-potential NH3 sensor based on Cu-doped Bi4V2O11 solid electrolyte for medium-low temperature applications

Cu-doped Bi 4 V 2 O 11 enabled medium-temperature mixed-potential NH 3 sensing. • Measurable NH 3 response appeared at 200°C, with optimum performance at 400°C. • Sensitivity increased with the conductivity of the solid electrolyte. The development of reduced operating temperature mixed-potential NH 3 sensors is hindered by insufficient ionic conductivity of conventional solid electrolytes at moderate temperatures. Here, a series of Cu-doped Bi 4 V 2-x Cu x O 11-δ (x = 0, 0.1, 0.2, 0.3) solid electrolytes were synthesized via a solid-state method to enhance oxygen ion transport. A mixed-potential NH 3 sensor was fabricated utilizing InVO 4 as the sensing electrode. Among the compositions, Bi 4 V 1.8 Cu 0.2 O 11-δ exhibited the highest conductivity, showing an over one order of magnitude increase at 400℃ compared with the undoped electrolyte. The resulting sensor showed a response to 10~300 ppm NH 3 over 200~550℃ and achieved a maximum sensitivity of −97.9 mV/decade at 400℃. Impedance/polarization analysis indicated that the sensing enhancement tracked the improved ionic transport of the Cu-doped electrolyte and followed the mixed-potential mechanism. This study highlights Bi 4 V 2-x Cu x O 11-δ -type electrolytes as promising electrolytes for moderate-temperature solid-electrolyte NH 3 sensing. Download: Download high-res image (148KB) Download: Download full-size image