Highly sensitive and selective room-temperature formaldehyde sensors using hollow TiO2 microspheres

Room temperature chemoresistive gas sensors could significantly decrease the demand of power consumption and are thus highly desirable in self-sustained nanosensors. Here we report that chemoresistive sensors fabricated from mesoporous hollow TiO2 microspheres show high sensitivity and selectivity to sub-ppm level of formaldehyde at room temperature with the assistance of low powered UV LED photon energy (2.5 mW). The sensor indicated excellent selectivity to other possible interferrents such as methanol, ethanol, acetone, ammonia and methylbenzene at low concentrations. These sensors have a much faster response (∼40 s)/recovery (∼50 s) characteristic, which significantly surpass the sensing properties shown by other types of nanostructured TiO2 reported in literature.