Ultralow Fe doping induced high photocatalytic activity toward ciprofloxacin degradation and CO₂ reduction

TiO₂ is one of the most ideal photocatalytic materials, but its application is limited by many problems (e.g., wide band gap, easy carrier recombination). Co-catalyst with changes in valence could efficiently overcome the disadvantages above. Herein, a Fe species (Fe, Fe₂O₃)/TiO₂ was designed to fully utilize photogenerated charges and holes. The degradation rate of ciprofloxacin can reach 99.97%. In addition, its methane generation from photoreduction of CO₂ is 12.9 times than that of pure TiO₂. These results are attributed to the well-designed catalyst including the combination of TiO₂ and FeO_x as photocatalysts and oxygen buffers, and the dispersion of single-atom Fe clusters as cocatalysts and electron trap sites. The effect mechanism of Fe species on TiO₂ was verified by PBE DFT calculation. Finally, following a concept of thermodynamic-kinetic synergy, a new design strategy for photocatalysts is accordingly proposed, as such, the prepared catalyst is expected to be applied in the environmental remediation.