ENGINEERING Fe-MODIFIED TiO2 NANOSTRUCTURES FOR TUNABLE CO2 PHOTOREDUCTION INTO CO AND CH4

The environmental impact of anthropogenic pollution has driven the search for efficient photocatalysts. Fe-decorated TiO 2 nanostructures were synthesized via hydrothermal method at controlled pH values (6, 8, and 10) followed by Fe impregnation (0.2 – 1.6 wt%), and evaluated for dye degradation and CO 2 photoreduction. XRD, Raman, and XPS confirmed anatase retention and atomically dispersed surface Fe 3+ species. Increasing Fe content decreased dye degradation but enhanced CO 2 photoreduction, showing an opposite trend explained by a unified Fe 3+ /Fe 2+ redox-trap mechanism: Fe 3+ captures electrons, prolonging charge separation; excess Fe 2+ scavenges holes, suppressing dye radicals while accumulating electrons for CO 2 reduction. Thermal treatment (400 °C for 4 h) improved performance in the pH 6 and 8 samples but not in the pH 10 sample or commercial TiO 2 . Samples prepared at pH 8 showed the best CO 2 photoreduction, attributed to a facet-driven surface heterojunction acting synergistically with Fe species. These findings establish design principles for tuning TiO 2 photocatalysts toward selective oxidation or reduction applications.