High ethanol sensitivity of Palladium/TiO2 nanobelt surface heterostructures dominated by enlarged surface area and nano-Schottky junctions

TiO2 nanobelts were prepared by the hydrothermal growth method. The surface of the nanobelts was coarsened by selective acid corrosion and functionalized with Pd catalyst particles. Three nanobelt samples (TiO2 nanobelts, surface-coarsened TiO2 nanobelts and Pd nanoparticle/TiO2 nanobelt surface heterostructures) were configured as gas sensors and their sensing ability was measured. Both the surface-coarsened nanobelts and the Pd nanoparticle-decorated TiO2 nanobelts exhibited dramatically improved sensitivity to ethanol vapor. Pd nanoparticle-decorated TiO2 nanobelts with surface heterostructures exhibited the best sensitivity, selectivity, working temperature, response/recovery time, and reproducibility. The excellent ethanol sensing performance is attributed to the large surface area and enhancement by Schottky barrier-type junctions between the Pd nanoparticles and TiO2 nanobelts.

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► TiO2 nanobelts and Pd/TiO2 heterostructure were synthesized.
► The nanobelts were made into gas sensors.
► The sensors show good sensitivity, especially high sensitivity, good selectivity.
► The sensing mechanism was explained using a surface-depletion model.