The presented work unravels the complex structure–function-relationships of Pt-loaded SnO₂, namely the sensitization by a Fermi-control mechanism and relation of catalytic activity and gas sensing effect.

The surface species responsible for NO₂ gas sensing over indium oxide was studied by operando DRIFTS coupled to a multivariate spectral analysis. It revealed the important roles of surface nitrites on the temperature-dependent gas sensing mechanism and the interaction of such nitrites with surface hydroxyls. A highly hydroxylated surface with high concentration of surface adsorbed H₂O is beneficial to enhance the concentration of adsorbed NO₂, present as nitrites, thus explaining superior sensing response at lower operating temperatures.