Asymmetrical Interactions between Ni Single Atomic Sites and Ni Clusters in a 3D Porous Organic Framework for...

3D porous organic frameworks, which possess the advantages of high surface area and abundant exposed active sites, are considered ideal platforms to accommodate single atoms (SAs) and metal nanoclusters (NCs) in high-performance catalysts; however, very little research has been conducted in this field. In the present work, a 3D porous organic framework containing Ni₁ SAs and Ni_n NCs is prepared through the metal-assisted one-pot polycondensation of tetraaldehyde and hexaaminotriptycene. The single metal sites and metal clusters confined in the 3D space created a favorable micro-environment that facilitated the activation of chemically inert CO₂ molecules, thus promoting the overall photoconversion efficiency and selectivity of CO₂ reduction. The 3D-NiSAs/NiNCs-POPs, as a CO₂ photoreduction catalyst, demonstrated an exceptional CO production rate of 6.24 mmol g^-1 h^-1, high selectivity of 98%, and excellent stability. The theoretical calculations uncovered that asymmetrical interaction between Ni₁ SAs and Ni_n NCs not only favored the bending of CO₂ molecules and reducing the CO₂ reduction energy, but also regulated the electronic structure of the catalyst leading to the optimal binding strength of intermediates.