Enhanced CO ₂ Photoconversion Efficiency in Atomic Co Immobilized Covalent Organic Frameworks Heterostructure via Boosting Charge Dynamics and Active Site Accessibility

Photocatalytic conversion of CO₂ into fuels and chemicals is of great significance for advancing sustainable development, yet its conversion efficiency remains constrained by inefficient charge separation and poor catalytic activity. Herein, a hybrid heterostructure is fabricated by in situ growth of bipyridine and triazine containing covalent organic frameworks (COFs) on SnS₂ nanosheets. Based on this heterostructure, a molecular engineering strategy is subsequently employed to design highly active single Co sites coordinated by bipyridine-N motifs featuring distinctive electronic moieties. As a result, the optimized photocatalyst (SnS₂/Co-TAPT-Bpy) enables an exceptional photocatalytic performance toward CO production under visible light irradiation with tunable CO/H₂ ration via changing the components of the heterojunctions. Experimental and theoretical investigations confirm that the photogenerated electrons can efficiently transfer from the SnS₂ component to the Co-TAPT-Bpy component through the interfacial electron field. More impressively, the electron-deficient triazine motifs in Co-TAPT-BPy direct these photogenerated electrons toward the Co (II) active sites for CO₂ reduction. These atomically dispersed N-Co-N sites enhance CO₂ activation and protonation through d-π orbital interactions, and suppress the competing H₂ evolution reaction, thus facilitating CO₂ conversion. This work highlights the potential of molecular regulation within heterojunctions to boost photocatalytic CO₂ conversion efficiency by optimizing charge dynamics and reaction site accessibility.