Self-Assembled SnO2/SnSe2 Heterostructures: A Suitable Platform for Ultrasensitive NO2 and H2 Sensing

Valentina Paolucci, Gianluca D'Olimpio, Chia Nung Kuo, Chin Shan Lue, Danil W. Boukhvalov, Carlo Cantalini, Antonio Politano

Research output: Contribution to journalArticle

Abstract

By means of experiments and theory, the gas-sensing properties of tin diselenide (SnSe2) were elucidated. We discover that, while the stoichiometric single crystal is chemically inert even in air, the nonstoichiometric sample assumes a subnanometric SnO2 surface oxide layer once exposed to ambient atmosphere. The presence of Se vacancies induces the formation of a metastable SeO2-like layer, which is finally transformed into a SnO2 skin. Remarkably, the self-assembled SnO2/SnSe2-x heterostructure is particularly efficient in gas sensing, whereas the stoichiometric SnSe2 sample does not show sensing properties. Congruently with the theoretical model, direct sensing tests carried out on SnO2/SnSe2-x at an operational temperature of 150 °C provided sensitivities of (1.06 ± 0.03) and (0.43 ± 0.02) [ppm]-1 for NO2 and H2, respectively, in dry air. The corresponding calculated limits of detection are (0.36 ± 0.01) and (3.6 ± 0.1) ppm for NO2 and H2, respectively. No detectable changes in gas-sensing performances are observed in a time period extended above six months. Our results pave the way for a novel generation of ambient-stable gas sensor based on self-assembled heterostructures formed taking advantage on the natural interaction of substoichiometric van der Waals semiconductors with air.

Original languageEnglish
JournalACS Applied Materials and Interfaces
DOIs
Publication statusAccepted/In press - 2020

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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