Highly-enhanced toluene gas-sensing behavior of high-valent metal-cations doped Co3O4 nanostructures derived from ZIF-67 MOF

In this paper, the different valent metal-cations (Zn 2 + , In 3 + and Zr 4 + ) doped porous Co 3 O 4 nanostructures were synthesized through the pyrolysis of ZIF-67 metal - organic framework (MOF). The influence of the different valence and doping content of metal-cations on the morphology, microstructures and gas-sensing performance of Co 3 O 4 sensors is discussed in detail. The Zr-doped Co 3 O 4 nanostructures present the higher specific surface area for the smaller average grain size, and the toluene gas-sensing performance of Co 3 O 4 nanostructures is significantly improved with the high -valent Zr-doping. The high valence Zr-doping greatly improves the toluene gassensing properties, which Co 2.717 Zr 0.189 O 4 sensor exhibits the highest response value of 94.58 to 100 ppm toluene gas (3.8-fold of Co 3 O 4 sensor). The donor Zr-doping to p -type Co 3 O 4 nanostructures optimizes the hole distribution and further affects Fermi level. Combining with the more oxygen adsorption from the high specific surface area, the resistance in air greatly decreases and resistance in toluene gas increases.