HCHO Sensing Mechanism of In4Sn3O12 Revealed by DRIFTS and DFT

The combination of operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy measurement and Density Functional Theory calculation reveals the counterintuitive HCHO sensing mechanism of In4Sn3O12. It is merely partial oxidation of HCHO into formate (or HCOOH) with medium activation energy (0.43–0.68 eV) and sufficient electron donation effect that is responsible for the sensor signal at the optimum temperature of 200 °C. The Sn (3a)-connected O is the active site and plays key roles in both HCHO adsorption and partial oxidation.