“…Up to date, typical yolk–shell nanostructures, defined as inner core@outer shell, integrating diverse functional components, such as Fe 3 O 4 @Carbon, [ 18 ] Fe 3 O 4 @SiO 2 , [ 19 ] Fe 3 O 4 @PMMA, [ 20 ] Au@PANI, [ 21 ] Au@Carbon, [ 22 ] Au@PNIPM, [ 23 ] Au@TiO 2 , [ 24 ] SiOx/Carbon, [ 25 ] Bi@Carbon, [ 26 ] and so on, have been developed. Among them, inner magnetic core, such as Fe 3 O 4 nanoparticles with strong magnetic responsivity and outer carbon shell with outstanding chemical stability, further functionalization and tunable pore structure were integrated to be one kind of most promising yolk–shell materials for facile drug targeting delivery, [ 27 ] rapid recovery of heterogenous catalysts in liquid phase, [ 28 ] rapid removal of metal ion and organic pollutants, [ 29,30 ] and rapid screening of biomolecules. [ 31 ]…”