High-entropy lead-free perovskite nanoparticles as efficient photocatalysis with a wide visible-light absorption band

Recently, metal halide perovskites have aroused burgeoning interest in the photocatalytic field. However, issues such as lead toxicity, and narrow absorption of visible light have limited their practical application. In this study, a high-entropy lead-free perovskite nanocrystals Cs(Mn 0.2 Ni 0.2 Sn 0.2 Co 0.2 Bi 0.1 )Br 3 were successfully obtained via a solvent-free synthetic route of high-energy ball milling. The influence of Bi content on the formation of single-phase high-entropy perovskite was investigated, demonstrated by characterization of XRD, XPS, and TEM. A reasonable synthesis mechanism was then proposed. Outperforming previously studied perovskite-based photocatalysts, Cs(Mn 0.2 Ni 0.2 Sn 0.2 Co 0.2 Bi 0.1 )Br 3 with a broad visible-light absorption band tuned by high-entropy multi-ions introduction, which exhibited outstanding photocatalytic activity under simulated visible light illumination, is reported here for the first time. The introduction of high-entropy had the triple benefit of prolonging the carrier lifetime, providing more active sites, and tuning the bandgap structure, which in turn is responsible for improving the photocatalytic activity. Finally, a removal efficiency for Rhodamine B of over 97 % within 60 min was obtained. In addition, the unequal molar ratio of Bi resulted in shallow surface defects, which induced lower carrier recombination. The active species involved was mainly the superoxide radical ( · O 2 − ) detected by the quenching experiment. Lastly, a possible photocatalytic mechanism was proposed. This work proposes a novel solution for metal halide perovskites to improve the photoelectric performance.