Facet-dependent photo-degradation of nitro polycyclic aromatic hydrocarbons on hematite under visible light: Participation of environmentally persistent free radicals and reactive oxygen/nitrogen species

In this work, we systematically explored the interfacial interactions between various NPAHs and hematite exposed with different facets under visible light. The results suggest that hematite nanocube (HNC) exhibited higher degradation rate for NPAHs, due to the greater number of electron accepting sites and reactive oxygen species (ROS). Notably, there are significant differences in the degradation pathways of various NPAHs. Envi-ronmentally persistent free radicals (EPFRs) were observed during the degradation of 9-nitroanthracene and 1-nitropyrene on hematite. The spin densities on HNC were higher than that on hematite nanoplate (HNP). Pe-riodic density functional theory (DFT) calculations indicated that the binding of radical intermediates on HNC is more favored than that on HNP. Meanwhile, NPAHs degradation was also accompanied by the production of various ROS and reactive nitrogen species (RNS). Overall, our findings provide theoretical guidance for the removal of NPAHs and the application of hematite photocatalysts for environmental remediation.

Automated summary

This work systematically investigated the interactions between hematite with different facets and various NPAHs under visible light. The results showed that hematite nanocube (HNC) exhibited a higher degradation rate for NPAHs due to its greater number of electron accepting sites and reactive oxygen species (ROS). Furthermore, the degradation pathways of different NPAHs were found to be significantly different. The findings of this study provide theoretical guidance for the removal of NPAHs and the application of hematite photocatalysts in environmental remediation.