Boosted Photocatalytic Activities of Ag₂CrO₄ through Eu³⁺-Doping Process

Ag₂CrO₄ is a representative member of a family of Ag-containing semiconductors with highly efficient visible-light-driven responsive photocatalysts. The doping process with Eu³⁺ is known to effectively tune their properties, thus opening opportunities for investigations and application. Here, we report the enhancement of the photocatalytic activity and stability of Ag₂CrO₄ by introducing Eu³⁺cations. The structural, electronic, and photocatalytic properties of Ag₂CrO₄:xEu³⁺ (x = 0, 0.25, 0.5, 1%) synthesized using the coprecipitation method were systematically discussed, and their photodegradation activity against rhodamine B (RhB), ciprofloxacin hydrochloride monohydrate (CIP), and 4-nitrophenol (4-NP) was evaluated. Structural analyses reveal a short-range symmetry breaking in the Ag₂CrO₄ lattice after Eu³⁺ doping, influencing the material morphology, size, and electronic properties. XPS analysis confirmed the incorporation of Eu³⁺ and alteration of the surface oxygen species. Furthermore, photoluminescence measurements indicated that the doping process was responsible for reducing recombination processes. The sample doped with 0.25% Eu³⁺ exhibited superior photocatalytic performance compared to pure Ag₂CrO₄. Scavenger experiments revealed an increase in the degradation via ^•OH reactive species for the sample doped with 0.25% Eu³⁺. DFT calculations provided atomic-scale insights into the structural and electronic changes induced by the Eu³⁺ doping process in the Ag₂CrO₄ host lattice. This study confirms that Eu³⁺ doping alters the band structure, enabling different degradation paths and boosting the separation/transfer of photogenerated charges, thereby improving the overall photocatalytic performance.