Single-Atom Cu Anchoring on Heterocyclic Ring of Metal-Organic Frameworks for Photocatalytic Nitrogen Fixation

Photocatalytic nitrogen fixation is a promising method for solving energy crisis and environmental problems. In this study, a straightforward approach to synthesize a single-atom catalyst CZ-1.5. The catalyst is developed through the formation of covalent bonds between copper atoms and a metal-organic framework (MOF). The experimental data have demonstrated that Cu binds to the MOF through the N on the ligand and the defect sites on the Zr oxide cluster. The CZ-1.5 shows the best nitrogen photofixation performance under ambient conditions and reaches 199.30 µmol g⁻¹ h⁻¹, which is 1.47 times than that of Zr-MOF. Density functional theory calculation combined with X-ray Absorption Fine Structure results reveal the possible hydrogenation pathway of single-atom active site. This work provides a new approach for the design of non-precious-metal single-atom photocatalysts that single atoms are bound to organic ligands and oxidation cluster defects of MOFs, which contribute to the advancement of sustainable development.