Water-stable perovskite nanotube array with enhanced transport of charge carriers induced by functionalized polyoxometalate for the highly efficient photoreduction of uranium(vi)

Abstract

Since metal halide perovskites (MHPs) possess excellent optoelectronic performances, constructing MHP-based photocatalysts is a promising strategy to promote photocatalytic uranium(VI) reduction. However, the instability of MHPs in water limits their practical application, which is still a major issue and challenge. In this work, we constructed a perovskite nanotube array-based catalyst encapsulated by a functionalized POM, (HMTA)₃Pb₂Br₇@STA-PW₁₂, which can maintain stability in water for 10 hours under stirring conditions. It is noteworthy that considering the “electron-sponge” property of POMs, STA-PW₁₂ acting as an electronic transfer medium not only increases the stability of the catalyst in water due to the hydrophobic long-chain STA but also contributes to the separation of photogenerated carriers and enhances charge transfer from (HMTA)₃Pb₂Br₇ to PW₁₂, which significantly enhances the photocatalytic activity. The enhanced electron carrier mobility (μ_e) (1.1 cm² V⁻¹ s⁻¹) and carrier diffusion length (245 nm) of (HMTA)₃Pb₂Br₇@STA-PW₁₂ further illustrate its effective charge carrier transfer. DFT calculations further indicate the transition of electrons from (HMTA)₃Pb₂Br₇ to PW₁₂, which greatly inhibits the recombination of photogenerated carriers, thereby advancing electron transfer. Finally, the synthesized catalyst exhibits an excellent performance in the photocatalytic removal of U(VI) with a removal rate of 99.3% at a U(VI) concentration of 40 ppm after 40 min under simulated sunlight.