Small oxygen sensor based on the combined technique of dispersed CeO2 nanoparticles with Pt nanogap electrodes

Abstract The investigation focused on a small resistive-type oxygen gas sensor composed of CeO 2 nanoparticles (NPs), combining a 30 nm nanogap electrodes technique. The Pt electrodes with the gaps of as small as 30 and 50 nm were fabricated on a thermally stable sapphire (α-Al 2 O 3 ) substrate. The electron hopping mechanism with the activation energies of 0.5–0.6 eV was observed for the CeO 2 NPs under investigation. The sensor conductance exhibited the logarithmic linear relationship with $${P_{{{\text{O}}_2}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>P</mml:mi> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:msub> </mml:math> over five digits. The value of the slope was approximately 0.26, corresponding to n = 4 in the $${P_{{{\text{O}}_2}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>P</mml:mi> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:msub> </mml:math> −1//n dependence in the oxygen-deficient metal oxide. The present oxygen gas sensor was utilized at the ambient pressure and at a relatively low operating temperature of 573 K, exhibiting the response time of t 80 less than 90 s. The nanomaterial-combined oxygen sensor demonstrates an example of the miniaturization of gas sensing devices that have the integrated flexible use in small space.