(A₁) The low magnification TEM image of penniform BaWO₄ nanostructures. (A₂) Locally enlarged TEM image of the shaft of the penniform BaWO₄ nanostructure. (A₃) Locally enlarged TEM image of the barbs of the penniform BaWO₄ nanostructure. The upper right inset shows the corresponding electron diffraction patterns of the main core and tufts. (A₄) A magnified image of the tuft portion of the penniform structure. Scale bars: (A₁) 2 μm; (A₂) 200 nm; (A₃) 100 nm; (A₄) 5 nm (Reproduced from Ref. [136]. Copyright©2003, American Chemical Society). (B)–(D) FM images of DSB-BPEA (B), DSB-BPNA (C), and BPEA-MCzT (D) highly branched superstructures. Scale bars: (B) 50 μm; (D) 10 μm. (B)–(D) Reproduced from Refs. [138–140], respectively. Copyright©2022, Wiley‐VCH GmbH; Copyright©2021, The Author(s); Copyright©2022, Royal Society of Chemistry. (E₁) SEM images of ZnO propeller-like nanostructures containing various symmetric structures marked as 6-, 4-, 2-fold. Scale bar is 3 μm (Reproduced from Ref. [141]. Copyright©2002, American Chemical Society). (E₂) SEM image of the ZnO nanopropeller array. (E₃) SEM image of the front view of the ZnO nanopropeller array (Reproduced from Ref. [142]. Copyright©2004, AIP Publishing). (F) Schematic representation of the formation of a hollow multi-level branch superstructures through metal-mediated fusion of TPEPA crystals. (G₁), (G₂) SEM images of TPEPA multi-level branch superstructure after 12 days of aging, showing the formation of complex branch structures and their hollow morphology. Scale bars: (G₁) 20 μm, inset 10 μm; (G₂) 5 μm, inset 1 μm. (H₁) SEM backscattered images of hollow TPEPA superstructures. Scale bars: left 1 μm, right 5 μm. (H₂) SEM secondary electron image (left) and mapping of copper by EDS-SEM (right) of a superstructure. Scale bars: 5 μm. (I) Right (1–5): schematic illustration of the process of recombination of TPEPA crystals into a multi-level branched superstructure as the reaction time continued. Right: Time-correlated ex situ SEM images showing specific changes in the fusion of TPEPA crystals into the superstructure. Inset: the evolution of the branch tip, showing the formation of the hollow topography. Scale bars are 10 and 500 μm (Reproduced from Ref. [143]. Copyright©2018, American Chemical Society).