Surface Modification of SnO ₂ Gas Sensors with WO ₃ for Temperature-Dependent Selective Detection of Ethanol and Acetone

Herein, we present a strategy for selective detection of volatile organic compounds (VOCs) by modulating the reaction pathways using SnO 2 -based gas sensors via loading with acidic WO 3 as the receptor material. The neat SnO 2 nanoparticles (NPs) were synthesized using hydrothermal treatment and calcination. Two methods were utilized to fabricate WO 3 –SnO 2 NPs: the impregnation method and mechanical mixing. The sensing responses to various VOCs were significantly improved by finely dispersed WO 3 -loaded SnO 2 compared to SnO 2 with low-dispersed WO 3 . Crucially, the introduction of WO 3 enhances the material’s surface acidity, which in turn changes the main reaction pathway of ethanol oxidation from dehydrogenation to dehydration. The interaction between WO 3 and SnO 2 NPs had a notable impact on sensor properties. WO 3 loading enhanced the response to ethanol by altering the reaction pathway at 350 °C and demonstrated selective detection of acetone at 250 °C due to its receptor effect. These findings highlight the importance of material design in SnO 2 -based sensors, where acidic oxide receptors like WO 3 effectively modulate the reaction pathway to enhance gas selectivity, offering valuable insights for developing selective gas sensors for medical diagnostics.