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

Abstract

Due to metal halide perovskites (MHPs) possess excellent optoelectronic performances, constructing MHPs based photocatalysts is a promising strategy to promote photocatalytic uranium(VI) reduction. However, instability of MHPs in water limits their practical application, which is still a major issue and challenge. In this article, we constructed a perovskite nanotube array-based catalyst encapsulated by functionalized POMs, (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 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 charges transfer from (HMTA)3Pb2Br7 to PW12, which enhance the photocatalytic activity significantly. The enhanced electrons carrier mobility (μe) (1.1 cm2 V-1 s-1) and carrier diffusion length (245 nm) of (HMTA)3Pb2Br7@STA-PW12 further illustrate its effective charge carriers’ 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 removal ratio of 99.3% in the U(VI) concentration of 40 ppm after 40 min under simulated sunlight.