Staggered ABC-Stacking Cobalt-Triptycene Framework for Accelerating CO₂ Photoreduction

Metal-organic frameworks (MOFs) are highly efficient photocatalysts due to their highly tunable structures and favorable electronic properties. However, achieving control over framework stacking arrangements, such as the staggered ABC-stacking, presents significant challenges. This difficulty arises from the inherently unfavorable energetics of the ABC arrangement and weaker π-π interactions compared to other stacking modes. Herein, a cobalt-triptycene framework with a staggered ABC-stacking arrangement was successfully synthesized in the aqueous phase, achieving a 90% yield. Experimental evaluations revealed that this framework achieved a CO production rate of 4.43 mmol g^-1 h^-1, which is comparable to the most reported MOF-based photocatalysts for CO₂ reduction. Moreover, density functional theory (DFT) calculations and molecular dynamics (MD) simulations indicated that the ABC-stacking cobalt-triptycene framework exhibits lower activation energy (0.079 eV) for water molecules, reduced Gibbs free energies for key intermediates *COOH (0.76 eV) and *H (0.73 eV), and the highest reaction rate increment (7.488 times). Furthermore, principal component analysis (PCA) reveals a strong correlation between the CO production rate and factors such as the Ik value, optical bandgap, and ΔG_*H, revising the previous held notion that ΔG_*COOH is the primary determinant of catalytic performance. These results offer valuable insights into the design principles of advanced photocatalysts for CO₂ reduction.