Construction
of suitable heterojunction oxide nanocomposites with
affluent porosities and distinctive microstructures is a primary approach
for acquiring high-performance sensing materials for specific gases.
In this work, certain Co3O4–TiO2 porous heterojunction nanosheets derived from bimetal–organic
frameworks (BMOFs) were constructed by calcining MIL-125 and ZIF-67
precursors with the goal of sensing ethanol. Sensing results showed
that BMOF-derived Co3O4–TiO2 porous nanosheets exhibited much better ethanol-sensing performances
than metal–organic framework (MOF)-derived TiO2 nanotablets.
The molar ratio of Co3O4 to TiO2 was
modulated to optimize the sensing performances of the Co3O4–TiO2 nanosheets. Under the conditions
of 250 °C and 50 ppm ethanol, the heterojunction nanosheets with
an optimal molar ratio of 12 mol % displayed the highest response
value of 41.72, which was 20.76 times higher than the response of
pure TiO2 nanotablets (2.01). Moreover, the selectivity
coefficient (85.29%) of 12 mol % Co3O4–TiO2 nanosheets was about 3.06 times as large as that of pure
TiO2 nanotablets (27.91%). The enhanced sensing performances
toward ethanol were mainly due to the formed p–n heterojunctions
and the porous nanosheet nanostructures with a high specific surface
area.