Summary A luminescent all-inorganic manganese-bismuth heterometallic Cs 4 MnBi 2 Cl 12 perovskite single crystal has been synthesized with a [BiCl 6 ] 3− -[MnCl 6 ] 4− -[BiCl 6 ] 3− triple-layered two-dimensional structure. Benefit from the effective energy transfer from [BiCl 6 ] 3 − octahedron donor to luminescent [MnCl 6 ] 4− acceptor, Cs 4 MnBi 2 Cl 12 shows a photoluminescence quantum yield (PLQY) of up to 25.7% (~610 nm), 51-fold higher than the Bi unalloyed CsMnCl 3 ·2H 2 O counterpart. Suggested by the theoretical calculations, Bi and Mn exhibit hybridization in conduction and valence band, which further results in a favorable low activation energy for exciton transfer (~23 meV). By virtue of all-inorganic chemical composition, Cs 4 MnBi 2 Cl 12 exhibits impressive stability toward moisture, light, and heat. Furthermore, Cs 4 MnBi 2 Cl 12 features strong soft X-ray attenuation and bright radiative luminescence under X-ray excitation, which pave a way for its application in medical flat-panel X-ray digital radiography. This work presents a new avenue toward fabrication of function-directed material with tailored photoelectric properties.
Lead-free halide double perovskites (LFHDPs) show great potential for solar-to-fuel conversion due to their unique photoelectrochemical properties, but they suffer from easy carriers recombination and insufficient active sites. In this work, a series of Co-doped Cs 4 MnBi 2 Cl 12 (denoting as Cs 4 MnCo x Bi 1-x Cl 12 ) microcrystals were synthesized for CO 2 photocatalytic reduction. Results of various characterizations, Kelvin probe microscopy mode (KPFM) and density functional theory simulation (DFT) calculations showed that Co doping into the Cs 4 MnBi 2 Cl 12 could induce spin polarization, resulting in fast carriers separation and extending carriers lifetime. The Cs 4 MnCo 0.9 Bi 0.1 Cl 12 (CMC 0.9 B 0.1 C) microcrystals exhibited the CO yield of 69.16 μmol·g −1 ·h −1 , which was 177 times of that of CMBC (0.39 μmol·g −1 ·h −1 ). Notably, CO 2 reduction performance from the CMC 0.9 B 0.1 C was significantly enhanced by applying an external magnetic field (300 mT) to the system, with CO yield reaching 99.96 μmol·g −1 ·h −1 . The main intermediates during CO 2 reduction were carboxylate (COOH*) and chelating-bridged carbonate (C-CO 3 2− ), and CO 2 reduction pathways and mechanism were proposed accordingly. These findings highlight the great potential of Co-doped Cs 4 MnCo x Bi 1-x Cl 12 as a promising photocatalyst for light-driven CO 2 reduction, opening up new avenues for the development of LFHDPs-based photocatalytic system.
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