Improved structure and gas sensing properties of ZIF-67 derived Co3O4 hollow porous polyhedra based on template-assisted growth

Gas sensing performances of MOF-derived metal-oxide-semiconductor were significantly affected by structural collapse and self-agglomeration. To solve the problem, ZIF-67 derived Co3O4 based on polystyrene sphere templates were prepared by room temperature precipitation and high temperature calcination. The prepared materials were characterized and analyzed by a variety of characterization methods. The results showed that the structure and dispersion of ZIF-67 derived Co3O4 were affected by template concentration. The optimized ZIF-67 derived Co3O4 showed a hollow porous polyhedral structure with the improved integrity, dispersion and stability of structure. The BET results showed that the optimized hollow porous polyhedra had the larger specific surface area and richer pores. Because of the improved material properties, the gas sensing performances was also greatly enhanced. The response of the optimized ZIF-67 derived Co3O4 to 10 ppm triethylamine was 6.72, while the response of ZIF-67 derived Co3O4 without template was only 3.81. Compared with the sample without template, the response time of the optimized ZIF-67 derived Co3O4 were shorter 27 s and the recovery time were shorter 154 s. Besides, the gas responses of the optimized sample with template showed a good stability and repeatability. The relative standard deviation of responses during 41 days was only 2.992 %. This work showed that the template-assisted growth is a promising way to enhance the structure and gas sensing properties of ZIF67 derived Co3O4.