A copper-manganese composite oxide as QCM sensing layers for detection of formaldehyde gas

A copper-manganese composite oxide was synthesized by controlling the molar ratio of Cu to Mn and calcination temperature. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and nitrogen adsorption-desorption measurements were employed to characterize the obtained products. The as-prepared copper-manganese composite oxide functionalized QCM resonators were fabricated and explored for HCHO sensing. The copper-manganese composite oxide functionalized QCM resonators had a significant response to HCHO, and the sensitivity of the resonators reached 6.35 Hz mg ppm)(-1). Neither the response nor the sensing profile observed significant changes after 60 days. The linear equation between the response of the QCM resonator and HCHO concentration endows the copper-manganese composite oxide functionalized QCM resonators with a capability of HCHO quantitative analysis. The adsorption-desorption process via hydrogen bonding between the oxygen of the copper-manganese composite oxide and HCHO molecules may be a plausible sensing mechanism for HCHO sensing.