An experimental and theoretical validation of dual role of Fe on improving the photocatalytic performance of doped mixed phase titania

The present work proposes a strategic approach of using Fe doping to form a mixed-phase TiO₂ direct Z-scheme catalyst at low onset temperature. The doping-induced modifications are explained from the experimental and theoretical viewpoint. Fe-doped Z-scheme-based mixed-phase TiO₂ at optimal calcination temperature (TiFe-400) exhibits maximum photon absorption and reduces charge carrier recombination, enhancing photocatalytic and PEC performance. TiFe-400 has the highest rate constant for the degradation of MB (0.084 min⁻¹ under solar irradiation) and showed exceptional photooxidation current (0.8 mA, 1.3 V vs Ag/AgCl). The Z-scheme formation significantly inhibits the recombination of photocarriers, resulting in a directed migration of charge carriers to the high redox potential mixed-phase TiO₂. This migration is validated by identifying the primary reactive species participating in the photocatalytic process. This work, demonstrating both experimental and theoretical approaches, may provide valuable insight into designing stable and inexpensive catalysts for dual applications on an industrial scale.