Gas sensor based on nanoporous hematite nanoparticles: Effect of synthesis pathways on morphology and gas sensing properties

The development of a low cost and scalable gas sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental pollution. In this work, we introduce two different synthesis pathways for the preparation of scalable Fe2O3 nanoparticles for gas sensor applications. One is co-precipitation and the other is hydrothermal method. The gas sensing properties of the α-Fe2O3 nanoparticles (NPs) fabricated by different synthesis pathways were studied and compared. The performance of the NPs in the detection of toxic and flammable gases such as carbon dioxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe2O3 NP-based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. However, the NPs fabricated by the one-step direct method exhibited higher sensitivities than those generated by the α-Fe2O3 NPs obtained by co-precipitation synthesis possibly because of their nanoporous structure. This performance is attributed to the large specific surface area of the NPs, which results in higher sensitivity.