fig3

Figure 3. (A) TEM images of the ZIF-8-TA at different etching times; (B) Schematic diagram of the formation mechanism for the cross-in-cube ZIF-8-TA. Reproduced with permission from ref.^[34]. Copyright 2021 American Chemical Society; (C) Schematic illustration of the synthesis process; (D-F) SEM and TEM images, magnified TEM image of 3S-mesoUiO-66-NH₂. Reproduced with permission from ref.^[35]. Copyright 2023 Springer Nature; (G) TEM images of multilevel structured APF resins with different volumes of ethanol and processing times. Scale bars = 200 nm. Reproduced with permission from ref.^[56]. Copyright 2022 Yutong Pi et al. Advanced Materials published by Wiley-VCH GmbH; (H) TEM images of SPR-1, SPR-2, SPR-3, YS-PR (180), HoMS-PR (180), and HM-PR (180). SEM images of YS-PR (180), HoMS-PR (180), and HM-PR (180). Reproduced with permission from ref.^[57]. Copyright 2023 Wiley-VCH GmbH. TA: tannic acid; SPR: the solid phenolicresins; YS-PR: Yolk-shell phenolic resins; HoMS-PR: hollow multi-shelled structure phenolic resins; HM-PR: hollow multi-stage phenolic resin.