Alteration of Internal Electron Migration Pathways in La-Doped Ag₃PO₄ for Improved Photocatalytic Stability

Abstract

Metal ion doping is an effective strategy to improve the charge carrier separation pathways in semiconductors. In this study, La3+ ions were introduced into Ag3PO4 via an in-situ co-precipitation method, forming P-type doped LaxAg3-xPO4 without altering the original cubic morphology of Ag3PO4. The introduction of La3+ led to a reduction in the band gap, an expansion of the light absorption range, and an increase in electron localization. Density functional theory (DFT) calculations revealed that La doping introduces new states within the band gap, facilitating energy transitions and altering the electronic structure. Time-dependent DFT (TDDFT) calculations confirmed that the introduction of La3+ enables photoexcited electrons to predominantly migrate from Ag 4d and O 2p orbitals to La 4d and P 2p orbitals. This key finding unveiled the anti-photocorrosion mechanism of LaxAg3-xPO4. Free radical capture experiments and electron paramagnetic resonance (EPR) analysis demonstrated that La doping enhances the electron migration efficiency in LaxAg3-xPO4, promoting the conversion of •O2⁻ to •OH radicals. This study not only provides an innovative approach for the application of La-doped Ag3PO4 in environmental pollutant catalysis but also reveals a novel internal electron transfer pathway and the underlying mechanism for enhanced photocatalytic activity.