MOF-Derived Hollow C, N-Doped Co3O4 Dodecahedral Nanostructure Enwrapped with MgIn2S4 Nanosheets for Enhanced Photocatalytic N2 Reduction

Design of hierarchical hollow nanoheterostructure materials through interfacial and defect engineering is an innovative approach for achieving optimal charge separation dynamics and photon harvesting efficiency. Herein, we have described a facile technique to fabricate hollow MOF-derived C, N-doped-Co₃O₄ (C, N-Co₃O₄) dodecahedral particles enwrapped with MgIn₂S₄ nanosheets for enhanced N₂ reduction performance. ZIF-67 was initially used as a sacrificial template to prepare hollow C, N-Co₃O₄ using a carbonization route followed by low-temperature calcination treatment. The controlled synthetic protocol not only led to nonmetal doping but also produced an interwoven carbon matrix that improved the photoelectron mobility. Density functional theory calculations further substantiated the creation of atomic defects through substitution of C at tetrahedral Co²⁺ sites and N at lattice O^2- sites of the Co₃O₄ structure. C, N-Co₃O₄ was subsequently coupled with MgIn₂S₄ nanosheets to prepare the C, N-Co₃O₄/MgIn₂S₄ [C, N-CM (X)] p-n heterojunctions. The photocatalytic study revealed that the NH₄⁺ ion production activity of the optimal C, N-CM (1:1) material (334 μmol g^-1 h^-1) was significantly higher (4-10 times) than that of pure components. The enhanced activity of the composite was ascribed to its distinct topological features, superior charge carrier dynamics, and creation of atomic defects that afforded a large number of surface-active sites.