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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
SEM images of Bi2S3 crystals in some stages of the self-assembly process. (a) Rolled-up worm formation and (b) sponge-like structure formation stage. Rectangles were added to the image (a) to indicate the unrolled (blue) and rolled-up worm (yellow) crystalline structures.