MOF-Derived Hollow C, N‑Doped Co<sub>3</sub>O<sub>4</sub> Dodecahedral Nanostructure Enwrapped with MgIn<sub>2</sub>S<sub>4</sub> Nanosheets for Enhanced Photocatalytic N<sub>2</sub> Reducti

Design\nof hierarchical hollow nanoheterostructure materials through\ninterfacial and defect engineering is an innovative approach for achieving\noptimal charge separation dynamics and photon harvesting efficiency.\nHerein, we have described a facile technique to fabricate hollow MOF-derived\nC, N-doped-Co<sub>3</sub>O<sub>4</sub> (C, N-Co<sub>3</sub>O<sub>4</sub>) dodecahedral particles enwrapped with MgIn<sub>2</sub>S<sub>4</sub> nanosheets for enhanced N<sub>2</sub> reduction performance. ZIF-67\nwas initially used as a sacrificial template to prepare hollow C,\nN-Co<sub>3</sub>O<sub>4</sub> using a carbonization route followed\nby low-temperature calcination treatment. The controlled synthetic\nprotocol not only led to nonmetal doping but also produced an interwoven\ncarbon matrix that improved the photoelectron mobility. Density functional\ntheory calculations further substantiated the creation of atomic defects\nthrough substitution of C at tetrahedral Co<sup>2+</sup> sites and\nN at lattice O<sup>2–</sup> sites of the Co<sub>3</sub>O<sub>4</sub> structure. C, N-Co<sub>3</sub>O<sub>4</sub> was subsequently\ncoupled with MgIn<sub>2</sub>S<sub>4</sub> nanosheets to prepare the\nC, N-Co<sub>3</sub>O<sub>4</sub>/MgIn<sub>2</sub>S<sub>4</sub> [C,\nN-CM (<i>X</i>)] p–n heterojunctions. The photocatalytic\nstudy revealed that the NH<sub>4</sub><sup>+</sup> ion production\nactivity of the optimal C, N-CM (1:1) material (334 μmol g<sup>–1</sup> h<sup>–1</sup>) was significantly higher (4–10\ntimes) than that of pure components. The enhanced activity of the\ncomposite was ascribed to its distinct topological features, superior\ncharge carrier dynamics, and creation of atomic defects that afforded\na large number of surface-active sites.