A nanocage-confined catalyst, characterized in that the catalyst has an active center of formula (I-1) and/or (I-2): M(Salenl)X (I-1) M' (Salen2) (I-2) such that the catalyst has formula (I): NC-m[M(Salen1)X]-n[M'(Salen2)] (I) wherein: NC is a material having a nanocage structure, wherein the NC is mesoporous silica nanoparticles having a nanocage structure or organic hybrid mesoporous silica nanoparticles having a nanocage structure; each occurrence of M is independently selected from the group consisting of Co ion, Fe ion, Ga ion, Al ion, Cr ion, and a mixture thereof; and each occurrence of M' is independently selected from Cu ion, Ni ion and a mixture thereof; m is an integer of 0 to 2, n is an integer of 0 to 1; provided that at least one of m and n is not 0; each occurrence of Salen1 and Salen2 is independently a derivative of a Shiff base; X is an axial anion, wherein each occurrence of X is independently selected from the group consisting of unsubstituted acetate, unsubstituted benzene sulfonate, p-toluenesulfonate, unsubstituted benzoate, F - , Cl - , Br - , I - , SbF 6 - , PF 6 - , BF 4 - and a mixture thereof; provided that: when X is an unsubstituted acetate, an unsubstituted benzenesulfonate, or an unsubstituted benzoate, then M is not a Co ion, when X is F - , Cl - , Br - , or I - , then m is not less than 2, and at least one occurrence of X in formula (I-1) is SbF 6 - , and the nanocage-confined catalyst does not have the formula FDU-12-Co(N,N'-disalicylidene-1,2-cyclohexanediamine)SbF 6 wherein the active center is encapsulated by prehydrolyzed methyl orthosilicate NC is a material having a nanocage structure, wherein the NC is mesoporous silica nanoparticles having a nanocage structure or organic hybrid mesoporous silica nanoparticles having a nanocage structure; each occurrence of M is independently selected from the group consisting of Co ion, Fe ion, Ga ion, Al ion, Cr ion, and a mixture thereof; and each occurrence of M' is independently selected from Cu ion, Ni ion and a mixture thereof; m is an integer of 0 to 2, n is an integer of 0 to 1; provided that at least one of m and n is not 0; each occurrence of Salen1 and Salen2 is independently a derivative of a Shiff base; X is an axial anion, wherein each occurrence of X is independently selected from the group consisting of unsubstituted acetate, unsubstituted benzene sulfonate, p-toluenesulfonate, unsubstituted benzoate, F - , Cl - , Br - , I - , SbF 6 - , PF 6 - , BF 4 - and a mixture thereof; provided that: when X is an unsubstituted acetate, an unsubstituted benzenesulfonate, or an unsubstituted benzoate, then M is not a Co ion, when X is F - , Cl - , Br - , or I - , then m is not less than 2, and at least one occurrence of X in formula (I-1) is SbF 6 - , and the nanocage-confined catalyst does not have the formula FDU-12-Co(N,N'-disalicylidene-1,2-cyclohexanediamine)SbF 6 wherein the active center is encapsulated by prehydrolyzed methyl orthosilicate when X is an unsubstituted acetate, an unsubstituted benzenesulfonate, or an unsubstituted benzoate, then M is not a Co ion, when X is F - , Cl - , Br - , or I - , then m is not less than 2, and at least one occurrence of X in formula (I-1) is SbF 6 - , and the nanocage-confined catalyst does not have the formula FDU-12-Co(N,N'-disalicylidene-1,2-cyclohexanediamine)SbF 6 wherein the active center is encapsulated by prehydrolyzed methyl orthosilicate <EOS>