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 Ag₃PO₄via an in situ co-precipitation method, forming p-type doped La_xAg_3−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 La_xAg_3−xPO₄. Free radical capture experiments and electron paramagnetic resonance (EPR) analysis demonstrated that La doping enhances the electron migration efficiency in La_xAg_3−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.