Effects of Addition of Cu_xO to Porous SnO₂ Microspheres Prepared by Ultrasonic Spray Pyrolysis on Sensing Properties to Volatile Organic Compounds

Porous (pr-)SnO2-based powders were synthesized by ultrasonic spray pyrolysis employing home-made polymethylmethacrylate (PMMA) microspheres (typical particle size: 70 nm in diameter), and effects of the CuxO addition to the pr-SnO2 powder on the acetone and toluene sensing properties were investigated. Well-developed spherical pores reflecting the morphology of the PMMA microsphere templates were formed in the SnO2-based powders, which were quite effective in enhancing the acetone and toluene responses. The 0.8 wt% Cu-added pr-SnO2 sensor showed the largest acetone response at 350 °C among all the sensors. Furthermore, we clarified that the addition of CuxO onto the pr-SnO2 decreased the concentration of carrier electrons and the acetone-oxidation activity, leading to the improvement of the acetone-sensing properties of the pr-SnO2 sensor