Nanoporous Co<sub>3</sub>O<sub>4</sub>–TiO<sub>2</sub> Heterojunction Nanosheets for Ethanol Sensing
Gang Li, Yuanyi Zhang, Qingfei Liang, Jinniu Zhang, Jia Liu, Yumeng Liu, Chunlan Wang, Jianzhi Gao, Hongbing Lu
Abstract
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.