(a) Schematic illustration of synthesis of TiO₂ TSHSs via hard-template method. Reproduced with permission from Ref. [78]. Copyright©2014, WILEY-VCH. (b) Illustration of the formation of HoMSs through STA. Reproduced with permission from Ref. [80]. Copyright©2018, WILEY-VCH. (c) Schematic illustration of the formation of different Cu₂O hollow structures in the presence of a CTAB template: (i) micelle; (ii) single-lamellar vesicle; (iii) multilamellar vesicle. Reproduced with permission from Ref. [84]. Copyright©2007, WILEY-VCH. (d) Schematic illustration of the synthesis procedure for CoSn(OH)₆ hollow nanoboxes via self-template method. Reproduced with permission from Ref. [90]. Copyright©2013, Springer Nature.