A Novel Porous Silicon Composite Sensor for Formaldehyde Detection

A novel palladium-porous silicon (Pd-PS) composite sensor was introduced for convenient and fast formaldehyde detection. Porous silicon was prepared by hydrothermal etching method and its surface micro-structure was characterized by scanning electron microscope. By optimizing the corrosion conditions of porous silicon, the optimum preparation conditions of porous silicon were obtained. In addition, palladium-porous silicon composite sensor was finally prepared by chemical immersion method to dope the metal palladium on the surface of porous silicon. When the prepared sensor was exposed to the mixed gas with formaldehyde, it exhibited a highly selectivity to formaldehyde molecules and could generate electrochemical signal that responded to the change of gas concentration. By detecting the electrical signal with a multimeter, the gas sensing properties of the sensor were investigated and discussed. The results indicated that the sensor was more sensitive to formaldehyde, exhibiting good selectivity. However, it was not sensitive to ethanol, ammonia, methanol and acetone. The detection rang of the sensor to formaldehyde concentration was 0.1-6.0 mg m(-3), with the detection limit of 0.1 mg m(-3) and detection time of 3 min.