In the present work, we investigated the acetone sensing characteristics and mechanism of SnO₂ thick-films through experiments and DFT calculations. SnO₂ thick film annealed at 600 °C could sensitively detect acetone vapors. At the optimum operating temperature of 180 °C, the responses of the SnO₂ sensor were 3.33, 3.94, 5.04, and 7.27 for 1, 3, 5, and 10 ppm acetone, respectively. The DFT calculation results show that the acetone molecule can be adsorbed on the five-fold-coordinated Sn and oxygen vacancy (VO) sites with O-down, with electrons transferring from acetone to the SnO₂ (110) surface. The acetone molecule acts as a donor in these modes, which can explain why the resistance of SnO₂ or n-type metal oxides decreased after the acetone molecules were introduced into the system. Molecular dynamics calculations show that acetone does not convert to other products during the simulation.
Keywords: SnO2; acetone; gas sensors; sensing mechanism.