Nanocomposites and nanomaterials

Semiconductor Ce-containing materials based on SnO2 for gas sensitive layers of H2 sensors
Fedorenko G.V. 1, Maksymovych N.P. 1, Oleksenko L.P.1, Vasylenko I.V. 2, Skolyar G.I. 1, Ripko O.P. 1
1 Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrs’ka str., 64/13, Kyiv-01601, Ukraine.
E-mail: georgf@ukr.net
2 L.V. Pisarzhevskii Institute of Physical Chemistry of National Academy of Sciences of the Ukraine, Prospect Nauki, 31, Kyiv-01601, Ukraine.

In recent years, research interest in hydrogen as a near-future fuel has increased because it is renewable, abundant, efficient, and unlike other alternatives, provides zero emissions that making Н2 to be the most environmentally friendly fuel. At the same time, hydrogen is an explosive gas, therefore, gas analysis devices, in particular based on semiconductor sensors, capable to detect the presence of H2 in air, are necessary in production, storage, transportation and usage of hydrogen. The main part of such sensors is semiconductor gas sensitive layer based mainly on tin dioxide with different catalytically active dopants.
To create the highly sensitive and fast hydrogen sensors and compare synthesis techniques semiconductor materials were synthesized by coprecipitation of tin dioxide and by Pechiney synthesis in order to obtain more sensitive semiconductor material. For coprecipitation technique antimony additives were added to the material during its synthesis in order to reduce an electrical resistance of the semiconductor. As a catalytically active dopant cerium was used due to its ability to promote formation of active oxygen during Ce4+  Ce3+ transition. The addition of cerium was carried out during the Pechiney synthesis and by wet impregnation of the sintered crystalline SnO2 for the coprecipitation technique.
The sensitivities of Ce-containing sensors are formed by formation on the surfaces of their gas sensitive layers of common boundaries between particles of cerium oxide and tin dioxide, which are active centers for oxygen chemisorption, that directly affects the sensitivities of the sensors and by manifestation of own  catalytic properties of CeO2.
It was established that Pechiney synthesis allows to obtain nanocomposite CeO2-SnO2 with SnO2 particles size up to ca. 30 nm and CeO2 particles size up to ca. 10 nm. Both methods allow to create adsorption semiconductor sensors capable to detect hydrogen presence in air in the wide concentration range.