Chiral nanomaterials have drawn extensive attention on account of numerous application prospects in optoelectronics, asymmetric catalysis, chiral recognition, and three-dimensional (3D) display. Thereinto, chiral perovskite has been a hotspot due to brilliant optoelectronic properties, but some problems limit the development, including low quantum yield, low chiral intensity, and the lack of facile regulation. To overcome these issues, an effective ligand exchange strategy, i.e. the interface modification has been proposed for chiral perovskite nanocrystals (PNCs). With the surface modification of CsPbBr3 PNCs with chiral organic ammonium in methyl acetate in the typical purification process, excellent circular dichroism (CD) signals were obtained and defects were eliminated, leading to an increase in the photoluminescence quantum yield (PLQY) from 50% to nearly 100%. The CD signal can be regulated through a ligand exchange strategy in the longitudinal dimension, the chiral intensity, and the transverse dimension, the wavelength range. Here, the proper addition of R-α-PEAI into the R-α-PEABr-capped CsPbBr3 PNCs can produce a superstrong CD signal with the highest anisotropy factor (g-factor) of 0.0026 in the visible region among reported chiral colloidal PNCs. Simultaneously, the luminescence emission can be tuned from the green to red region with boosted PLQY through the approach. The density functional theory (DFT) calculation result supports that chirality comes from the hybridization between the energy level of a perovskite structure and that of chiral organic molecules. These properties can be used in the structural engineering of high-performance chiral optical materials, spin-polarized light-emitting devices, and polarized optoelectronic devices.

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Coupling heterojunction is an effective and feasible approach to suppressing the electron–hole recombination of a photocatalyst. However, the heterojunction performance is limited by poor interface contact between two semiconductors. Therefore, an in situ partial conversion procedure was proposed to fabricate the flower-spherical BiOI/Bi5O7I (BBOI) heterojunction using bacitracin as a template. The introduction of bacitracin can regulate the assembly of nanosheets into a flower-spherical structure, which caused the BBOI photocatalysts to have larger specific surface areas than BiOI or Bi5O7I. In particular, the dosage of bacitracin can control the thermal conversion of BiOI to Bi5O7I. The in situ partial conversion of BiOI caused the formation of an intimate S-scheme heterojunction interface between BiOI and Bi5O7I, which efficiently inhibited the combination of photogenerated carriers. Upon visible-light irradiation, BBOI-3 exhibited the highest catalytic ability for the simultaneous reduction of Cr­(VI) (100%) and oxidative degradation of tetracycline hydrochloride (TH) (80.0%). This work provides an opinion to construct the high-performance heterojunction photocatalysts to environmental remediation.

The novel Z-scheme flower-like Bi5O7I/Bi4Ti3O12 composites were prepared via in-situ grown under hydrothermal-calcination method, which were exhibited outstanding photocatalytic performance for selective oxidation of benzylic alcohols.

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