Characterization of optical, chemical, and structural changes upon reduction of sol-gel deposited SnO2 thin films for optical gas sensing at high temperatures

► Reduction of SnO2 thin films at temperatures of approximately 500 °C and above. ► Early stage SnO2 film reduction occurs through Sn-enriched nanoparticle formation. ► SnO2 optical transmission changes correlate with the onset of film reduction. ► SnO2 stability limits high temperature reducing environment sensing applications.