Insight into the Co and N statuses in MOF-derived porous carbonaceous materials in catalytic ozonolysis at room temperature

Abstract

Ozone is one of the classical atmospheric pollutants that adversely affects human health and the ecological environment. In this paper, carbonaceous catalysts derived from MOFs with different structural topologies and organic ligands were systematically investigated for ozone elimination. Upon carbonization, ZIF-67-NC was formed with a rich microporous structure and N doping in the corresponding carbon support. N doping facilitated the further dispersion and redox behavior of the active Co²⁺ cations. Moreover, the high nitrogen content promoted the formation of more defective sites in ZIF-67-NC, which can facilitate the formation of Co–N structure and bring the highest content of these active centers. Furthermore, a large number of microporous structures is beneficial for the exposed Co–N active sites and enhanced the O₃ adsorption, leading to a better activity and stability. The ZIF-67-NC exhibited an ozone conversion close to 100% at a concentration of 40 ppm O₃ and 50% relative humidity for 16 h. In situ DRIFTs and theoretical calculations confirmed the excellent capacity for O₂²⁻ and O₂⁻ desorption of ZIF-67-NC. The lowest energy barrier and weakest O₂ adsorption strength enabled an efficient O₃ decomposition and successive O₂ desorption.