• Monteiro, Teresa
• Mishra, Yogendra Kumar
• Mishra, Abhishek Kumar
• Rodrigues, Joana
• Leeuw, Nora H. De
• Gröttrup, Jorit
• Ababii, Nicolai
• Lupan, Oleg
• Adelung, Rainer
• Sontea, Victor
• Sedrine, Nebiha Ben
• Postica, Vasile
• Correia, Maria Rosário
• Carreira, José F. C.

Abstract

<p>Hybrid metal oxide nano- and microstructures exhibit novel properties, which make them promising candidates for a wide range of applications, including gas sensing. In this work, the characteristics of the hybrid ZnO-Bi₂O₃ and ZnO-Zn₂SnO₄ tetrapod (T) networks are investigated in detail. The gas sensing studies reveal improved performance of the hybrid networks compared to pure ZnO-T networks. For the ZnO-T-Bi₂O₃ networks, an enhancement in H₂ gas response is obtained, although the observed p-type sensing behavior is attributed to the formed junctions between the arms of ZnO-T covered with Bi₂O₃ and the modulation of the regions where holes accumulate under exposure to H₂ gas. In ZnO-T-Zn₂SnO₄ networks, a change in selectivity to CO gas with high response is noted. The devices based on individual ZnO-T-Bi₂O₃ and ZnO-T-Zn₂SnO₄ structures showed an enhanced H₂ gas response, which is explained on the basis of interactions (electronic sensitization) between the ZnO-T arm and Bi₂O₃ shell layer and single Schottky contact structure, respectively. Density functional theory-based calculations provide mechanistic insights into the interaction of H₂ and CO gas molecules with Bi- and Sn-doped ZnO(0001) surfaces, revealing changes in the Fermi energies, as well as charge transfer between the molecules and surface species, which facilitate gas sensing.</p>

Topics

• density
• impedance spectroscopy
• microstructure
• surface
• theory
• density functional theory