Electron transfer enhancing the Mn(II)/Mn(III) cycle in MnO/CN towards catalytic ozonation of atrazine via a synergistic effect between MnO and CN

In this study, manganese oxide (MnO) dispersed on CN (Mn-nCN) was fabricated as a catalyst in heterogeneous catalytic ozonation (HCO), achieving excellent catalytic performance on refractory organic pollutant degradation via the synergistic effects between MnO and CN. The study demonstrated that the C-N- Mn and C-O-Mn bonds constructed in the catalyst linking MnO and CN created the synergistic effects which could overcome typical problems, such as metal leaching etc. The C-N-Mn and C-O-Mn bonds could promote electron transfer from cation-pi reactions to form electron-rich Mn(II) sites and electron-poor CN sites. The electron-rich Mn(II) sites as active sites supplied electrons to ozone which then further evolved into reactive oxygen species (ROS). The electron-poor CN sites captured electrons from the pollutant intermediate radicals to electron-rich Mn(II) sites via cation-pi reactions with the help of C-N-Mn and C-O-Mn bonds, which promote the redox reactions of Mn. The surface hydroxyl groups also participated in ozone decomposition and ROS production. Additionally, center dot OH was the dominant ROS of the Mn-nCN HCO processes. This study presents the excellent HCO performance of Mn-nCN, as well as provides views on the electron transfer route between the catalyst, pollutant and ozone, which is crucial for the design of the catalyst.

Automated summary

In this study, a new type of hybrid material Mn-nCN, composed of manganese oxide (MnO) dispersed on carbon-nitrogen (CN) material, was fabricated as a catalyst for heterogeneous catalytic ozonation (HCO) and showed excellent catalytic performance in degrading refractory organic pollutants. The synergistic effects between MnO and CN, facilitated by the C-N-Mn and C-O-Mn bonds in the catalyst, overcome typical issues such as metal leaching, and promote redox reactions of Mn by promoting electron transfer from cation-pi reactions. The study also demonstrated the involvement of surface hydroxyl groups in ozone decomposition and reactive oxygen species (ROS) production.