Highly stable halide perovskite with Na incorporation for efficient photocatalytic degradation of organic dyes in water solution

To overcome water instability and low photocatalytic activity of lead-free halide perovskite for the degradation of organic dyes, we report a novel photocatalyst of lead-free halide perovskite with Na incorporation and employ it for the photocatalytic degradation of organic dyes in water solution under visible light irradiation. The main purpose of this work is to confirm the feasibility of lead-free halide perovskite with Na incorporation for improving the photocatalytic efficiency and recyclability in water solution and further to explore the mechanism behind the enhancement of photocatalytic performance after Na incorporation. The results show that Cs₂Ag₀.₆₀Na₀.₄₀InCl₆ can increase the dye degradation rate by at least 50% than the lead-free halide perovskite (Cs₂AgInCl₆) and the photocatalyst of Ag substituted by Na (Cs₂NaInCl₆). The degradation efficiency of rhodamine 6G catalyzed by Cs₂Ag₀.₆₀Na₀.₄₀InCl₆ reaches 94.94% over 60 min, which is 72% higher than that catalyzed by Cs₂NaInCl₆ and 27% higher than that catalyzed by Cs₂AgInCl₆. What’s more, the degradation efficiency of methyl orange catalyzed by Cs₂Ag₀.₆₀Na₀.₄₀InCl₆ is 90.39% within 150 min, which is 66% higher than that catalyzed by Cs₂NaInCl₆ and 54% higher than that catalyzed by Cs₂AgInCl₆. Moreover, the photocatalyst of Cs₂Ag₀.₆₀Na₀.₄₀InCl₆ exhibits a desirable recyclability by water exposure, retaining the degradation efficiency over 90% after five cycles. The strengthened photocatalytic performance in the presence of Cs₂Ag₀.₆₀Na₀.₄₀InCl₆ is ascribed to an increase of radiative recombination rate and an improvement of average lifetime to 204 ns since an appropriate Na incorporation at the atomic ratio of Na/Ag=4:6 breaks the original crystal lattice and meanwhile increases the electron and hole overlap. The work proves a great potential of halide perovskite with Na incorporation for the highly efficient photocatalytic degradation of organic dyes in water solution.