A bioinspired polyoxo-titanium cluster for efficient photocatalytic CO₂ reduction assisted by hydrogen bonding

Designing functional sites with well-defined and directional photocatalytic activities is crucial for efficiently utilizing spatially separated photogenerated charge carriers and achieving high photocatalytic performance. Herein, inspired by natural photosynthesis, we successfully developed a series of phosphonic acid functionalized polyoxo-titanium clusters. We uncover the pivotal role of strategically positioning noncovalent interactions surrounding the catalytic center in regulating the CO₂ reduction performance. Remarkably, introducing amino groups in synergy with proton-rich phosphate moieties near the cobalt-nitrogen active site leads to a six-fold enhancement in photocatalytic CO₂ reduction activity. Among them, the modified cluster NH₂-BQTiCo delivers an exceptional CO₂ photoreduction performance under visible light, achieving a CO production rate as high as 1456 µmol g^-1 h^-1. Combining experimental results with DFT calculations reveals that strong intermolecular hydrogen-bonding traction around the catalytical center can significantly strengthen CO₂ adsorption and facilitate a smoother activation pathway. This work highlights a biomimetic design strategy to optimize electron delocalization within polyoxo-titanium clusters, thereby promoting efficient intramolecular charge transfer and advancing high-performance CO₂ photoreduction.