Double-shelled　hollow　structures　possess　unique　properties　in　energy　conversion/storage　fields　due　to　their　higher　surface　area,　larger　contact　region　with　the　electrolyte　and　much　shortened　paths　of　charge　transfer.　In　this　work,　CoMoSx@Ni-CoMoSx　hollow　polyhedron　catalyst　with　a　double-shelled　cage-in-cage　structure　is　prepared　by　a　sequence　of　template-engaged　synthetic　processes.　In　the　synthetic　procedure,　(NH4)2MoS4　is　applied　as　a　multifunctional　vulcanizator,　which　can　conveniently　afford　Mo　and　S　elements　at　the　same　time.　Noteworthily,　by　comparing　with　single-shelled　hollow　CoMoSx　and　Ni-CoMoSx　polyhedrons,　the　double-shelled　CoMoSx@Ni-CoMoSx　polyhedron　catalyst　demonstrates　superior　catalytic　properties　in　the　reduction　of　triiodide　in　dye-sensitized　solar　cells.　The　solar　cell　with　CoMoSx@Ni-CoMoSx　based　counter　electrode　exhibits　a　high　power　conversion　efficiency　of　9.30%,　which　is　much　higher　than　that　of　Pt　(8.01%).　©　2019　Elsevier　B.V.