Mechanism insight into oxygen vacancy-dependent effect in Fe1/TiO2 single-atom catalyst for highly enhanced photo-Fenton mineralization of phenol

This study develops a highly efficient Fe1/TiO2-OV single-atom catalyst to explore the synergistic effect in the photo-Fenton mineralization of phenol. Via using diverse in-situ spectroscopies and density functional theory calculations, the catalytic mechanism is unraveled. That is, oxygen vacancies can significantly accelerate photogenerated charge separation and oriented delivery to Fe1 single atoms for fast generation of reactive oxygen species, as well as promote the selective adsorption/activation of phenol. As a result, the C-H bonds on phenol were deeply oxidized (conversion: > 91%), accompanied by the mineralization of the benzene ring, with CO2 and H2O as end products (mineralization rate: 66%). Such concerted catalysis between Fe single atoms and oxygen vacancies results in a high reactivity for phenol photo-Fenton mineralization, which is superior to most reported transition-metal-based catalysts. Our finding is expected to provide guidance for designing high-efficiency heterogeneous catalysts in the photo-Fenton catalytic process.