Metal/SnO2 interface effects on CO sensing; operando studies

The influence of the electrode nature on the performance of semiconducting metal oxide based gas sensors is recognized and experimentally proven. Here, for the first time we are providing clear spectroscopic evidence (DRIFTS) for the influence of the electrode nature (Pt and Au) on the surface chemistry associated to CO detection with SnO₂ thick film sensors. Our results show that the nature and concentration of the CO reaction intermediates (carbonates and carboxylates) depend on the presence and nature of the electrodes; moreover, we found that the simple presence of the metals in the sensing layers does not have similar effects, which indicates that the electrodes´ polarization is to be taken into account.