Rational structure transformation triggered by titanium modulation in metal-organic frameworks for efficient flue gas utilization

Titanium-based metal-organic frameworks (MOFs) have received more attention for CO2 capture and utilization because of their excellent stability and photoactivity, but they are limited by the high reactivity of Ti(IV) during their crystallization. Herein, we propose a titanium modulation strategy for rationally designing a series of Ti-modulated MOFs (TiM-MOFs and SNNU-90–92). Ti(IV) as a modulator changed the coordination equilibrium and regulated the inorganic building blocks from Co4(OH)4(COO)4 to Co3-xTixO(COO)6 and Co6-xTix(O/OH)6(COO)6, triggering a continuous structure transformation with high-quality single crystal. The CO2 adsorption, separation, and catalytic properties of TiM-MOFs in flue gas were significantly improved over those of monometallic MOFs. Remarkably, TiM-MOFs can effectively convert flue gas to cyclic carbonates via photocatalysis with excellent yield and turnover efficiency, making them superior to all state-of-the-art MOF catalysts. Rational structure modulation, controllable Ti(IV) content, and extortionary chemical conversion efficiency make TiM-MOFs ideal candidates for the comprehensive utilization of flue gas.