Mechanism of ozone adsorption and activation on B-, N-, P-, and Si-doped graphene: A DFT study

The detailed evolution mechanism of O-3 into Reactive oxygen species (ROS) is of paramount importance but remains elusive in catalytic ozonation. Herein, we report a density functional theory study to comprehensively reveal the specific evolution processes of O-3 into ROS on the B-, N-, P-, and Si-doped graphene, including the adsorption, decomposition and ROS generation. In contrast to some previous reports that O-3 would directly decompose into effective ROS on catalysts, our results indicate that after O-3 adsorption, the decomposition products are ground state O-2 and the adsorbed oxygen species (O-ads). The O-ads is more likely to act as a crucial intermediate for generating other ROS instead of directly attacking the organics. The type of the ROS and generation efficiency vary with the doped heteroatoms, and the heteroatoms of B, P and Si, or the neighboring C of N, would serve as active sites for O-3 adsorption and decomposition. The N-and P-doped graphene are predicted to have the superior performance in ROS generation and catalytic stability. Finally, twenty representative descriptors were adopted to build the quantitative structure-activity relationship (QSAR) with the activation energy barrier of O-3 decomposition. The result indicates that condensed dual descriptor (CDD) could be useful for preliminarily selecting the modified graphene catalysts, since it shows a very good linear relation with the activation energy barrier. This contribution provides an alternative way to gain fundamental insights into the mechanism of catalytic ozonation at the molecular level, and could be helpful for designing more-efficient catalysts in environmental remediation