Novel mesoporous filters for selective gas absorption

Semiconductor gas sensors have a proven potential for low cost and highly sensitive gas detection. However, selectivity remains one of the main problems for many applications. We report a new kind of mesoporous ceramic filter with nanoscale pores. The ceramic filter offers mechanical protection and can help to boost selectivity enormously through selective gas absorption. The developed nano-technological filters are based on mesoporous secondary and ternary silicon nitride derivatives with a defined particle size and are prepared via a new sol gel route. The interaction of the filters with CO, NO/sub 2/, H/sub 2/ and propane were evaluated using broadband sensors. Highly selective absorption was observed for different gases, especially NO/sub 2/. From these experiments a filter efficiency value is calculated, which allows easy selection of suitable filter materials for different applications.