Modulating electron density enable efficient cascade conversion from peroxymonosulfate to superoxide radical driven by electron-rich/poor dual sites.

The superoxide radical (•O)-mediated peroxymonosulfate (PMS)-based photo-Fenton-like reaction enables highly selective water decontamination. Nevertheless, the targeted construction of •O-mediated photo-Fenton-like system has been challenging. Herein, we developed an electron-rich/-poor dual sites driven •O-mediated cascade photo-Fenton-like system by modulating electron density.

Spin state-dependent in-situ photo-Fenton-like transformation from oxygen molecule towards singlet oxygen for selective water decontamination.

The development of O-dominanted selective decontamination for water purification was hampered by extra HO consumption and poor O generation. Herein, we proposed the reconstruction of Fe spin state using near-range N atom and long-range N vacancies to enable efficient generation of HO and sequential activation of HO into O after visible-light irradiation. Theoretical and experimental results revealed that medium-spin Fe(III) strengthened O adsorption, penetrated e electrons to antibonding p-orbital of oxygen, and lowered the free energy of O activation, enabling the oxygen protonation for HO generation.