Synthesis of hierarchically macro-mesoporous CoTiO₃ with improved gas sensing properties

Hierarchically porous CoTiO₃ powders with interconnected framework composed of nanoparticles as high performance gas sensing materials for ethanol were prepared by sol-gel method with C₄H₁₁NO₂ (DEA) as the chelating agent. A characteristic of hierarchical pore size distribution with both mesopores ranging from about 2 to 10 nm and macropores approximately from 0.15 to 3 μm can be found within the porous CoTiO₃ powders prepared at a molar ratio of DEA to Ti and Co of 1.6 : 1 : 1. The formation of macropores is mainly depending on the pore characteristics of gel skeletons before calcination, while the mesopores within macropore walls are generated after calcination. The sensing performances of porous cobalt titanate with different pore structure characteristics were compared based on the fabricated gas sensors. The hierarchically porous CoTiO₃ powders with a specific surface area of 47.04 m² g⁻¹ demonstrate the maximum response (71.5) towards 100 ppm ethanol at 420 °C. The corresponding response and recovery time are about 15 and 22 s, respectively. (paper)