Introduction of a Pore Connection Network into Mesoporous TiO2 Films to Enhance CO Gas Sensitivity

Abstract

In this work, ordered mesoporous TiO2 films with interior pore connections were fabricated. To introduce the interior pore connections, the grain growth of TiO2 on the pore wall structure was controlled by increasing the annealing time. In the annealing process, the growth of TiO2 grains was enhanced, and interior pores were connected by a meso-channel formed during the growth of TiO2 grains. As a result, with increasing annealing time, the specific surface area of the mesoporous TiO2 films increased by a factor of 3, although the porosity decreased. When the ordered mesoporous TiO2 film with enhanced pore connectivity was applied in a CO gas sensor, the gas sensitivity increased by a factor of almost 20 due to the enhanced pore connectivity resulting from controlled annealing time. The introduction of pore connectivity in a closed pore structure may be an advantageous method in various fields where a large surface area is required for nanoporous structured materials.