Sub-stoichiometric WO2.9 as co-catalyst with platinum for formaldehyde gas sensor with high sensitivity

The detection of formaldehyde (HCHO) in indoor environment is becoming more and more important. Here, a novel composites catalyst based on platinum and tungsten oxide was prepared for electro-oxidation of formaldehyde and used to design a simply equipped amperometric gas sensor. Considering that the modulation of atomic structure could effectively improve the properties of materials and enhance catalytic capability, we have regulated the local atomic structure of a commercial product of WO3 into the highly active sub-stoichiometric WO2.9 to be an efficient co-catalyst through a facile thermal treatment. Pt-WOX (X = 3, 2.9) nanocomposites were prepared by physical ultrasound and further characterized by XRD, XPS, TEM, SEM techniques. The electro-catalytic oxidation of formaldehyde at the Pt-WOX modified glassy carbon electrode was studied by cyclic voltammetry. Pt-WO2.9 (15%) exhibited better electrochemical activity with a higher oxidation peak current of 1.5 mA than that of Pt-WO3 (15%) and pure Pt. It is worth noting that reducing the platinum content in catalysts improves the catalytic activity. The Pt-WO2.9 based formaldehyde sensor displays a high sensitivity of 53 μA/ppm and good reproducibility and stability. Thanks to the tailored electronic structure (oxygen vacancies) of tungsten oxide, the as-prepared Pt-WO2.9 nanocomposites might become a promising candidate for practical application of detecting formaldehyde.