Interaction of Water Vapor with SnO2 Sensor Materials: A Comparison of DRIFTS and Resistance Measurements

Operando DRIFT spectroscopy together with resistance measurements was used to study sensitivity (here response change upon changing analyte concentration) of undoped SnO2 materials to water vapors. The materials synthesized using different protocols were found to manifest very different sensitivity to water, as well as to H2 and CO in dry and humid air. While for one of the materials (SnO2 Ac) low sensitivity to water combines with similarity between evolution of two bands in OH region and resistance, another material (SnO2 Cl), with high sensitivity to water vapors, manifests similarity with the resistance only for the broad band between 3590 and 3040 cm-1. Together with high sensitivity to water vapors the latter material shows higher sensitivity to CO in dry and humid air, while SnO2 Ac showed higher sensitivity to H2.