Strategies used to obtain hollow structures fall into three categories: hard templating, soft templating, and self-templating . Hard templating synthesis is usually based on three successive steps: (i) hard-template preparation in a specific format, (ii) coating/depositing (selective) of the target material on the template, and (iii) selective mould removal to obtain hollow and open structures, usually by calcination, dissolution, or chemical corrosion. At the same time, it is known that soft-template synthesis is thermodynamically metastable with high deformability owing to its liquid/gaseous form.