One-step approach for preparing ozone gas sensors based on hierarchical NiCo2O4 structures

RSC Adv., 2016, volume 6, issue 95, pages 92655-92662, The Royal Society of Chemistry

Fig. (a and b) FESEM images of NiCo2O4 platelets annealed at 450°C for 2h under an ambient atmosphere

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Writers: Joshi, Nirav and da Silva, Luis F. and Jadhav, Harsharaj and M’Peko, Jean-Claude and Millan Torres, Bruno Bassi and Aguir, Khalifa and Mastelaro, Valmor R. and Oliveira, Osvaldo N.

Keywords: gas sensor; ozone; oxide

Abstract: Nanostructured semiconducting oxides have been used as resistive gas sensors of toxic and non-toxic gases{,} but little emphasis has been placed on ozone sensing. Here we present a new ozone gas sensor based on hierarchical NiCo2O4 cubic structures synthesized via a facile urea-assisted co-precipitation method and annealed at 450 [degree]C{,} which showed a low detection level. Ozone detection was carried out through electrical measurements with an optimized performance at 200 [degree]C{,} with fast response ([similar]32 s) and recovery ([similar]60 s) time with suitable concentration range (from 28 to 165 ppb) for technological applications. Furthermore{,} NiCO2O4 platelets are selective to ozone compared to other oxidizing and reducing gases. The low detection level can be attributed to the coexistence of 3D structures based on hexagonal platelet-like and porous flower-like shape{,} which were revealed by field emission scanning electron microscopy (FE-SEM). In summary{,} NiCo2O4 is promising for detection of sub-ppb levels of ozone gas.

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