Formaldehyde Sensing Characteristics of a NiO-Based Sensor Decorated With Pd Nanoparticles and a Pd Thin Film

A Pd nanoparticle (NP)/Pd film/NiO film structure, prepared with both drop-coating and RF sputtering approaches, is reported to fabricate a formaldehyde gas sensor. As compared to pristine NiO layers, the use of Pd NPs and Pd thin film is shown to enhance the catalytic capability and related sensing performance. Experimentally, a high sensing response of 10.1 is obtained under introduced 20 ppm HCHO/air gas at 250 °C. Moreover, a very low detection level of 16 ppb HCHO/air is acquired. The optimal operating temperature is 250 °C. Due to the nonuniform distribution or agglomeration effect of Pd NPs, a relatively slow sensing speed is found. Based on the superior performance indicated earlier and advantages including low cost, easy fabrication, and chemical stability, the studied device is promising for formaldehyde sensing applications.