HCHO Sensing Mechanism of In₄Sn₃O₁₂ Revealed by DRIFTS and DFT

The combination of operando Diffuse Reflectance InfraredFourierTransform Spectroscopy measurement and Density Functional Theory calculationreveals the counterintuitive HCHO sensing mechanism of In4Sn3O12. It is merely partial oxidation of HCHOinto formate (or HCOOH) with medium activation energy (0.43-0.68eV) and sufficient electron donation effect that is responsible forthe sensor signal at the optimum temperature of 200 degrees C. The Sn(3a)-connected O is the active site and plays key roles in both HCHOadsorption and partial oxidation.