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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 …
American Chemical Society
Publication date: 
14 Jul 2020

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

Biblio References: 
ACS Applied Materials & Interfaces