Title : A universal framework for ligand-directed artificial photosynthesis by hydrolyzed titanium complexes: Toward autonomous CO2 capture and conversion under ambient conditions
Abstract:
A general framework is presented for artificial photosynthesis based on hydrolyzed titanium–ligand systems that operate as self-organizing, redox-active ensembles under ambient conditions. Unlike conventional photocatalytic approaches that rely on engineered surfaces or external inputs, these systems emerge spontaneously from TiCl4–ligand precursors upon exposure to air, moisture, and visible light, forming dynamically evolving matrices capable of simultaneous CO2 capture and conversion.
Within this framework, hydrolysis generates Ti–OH, Ti=O, and Ti–O–Ti motifs in a chloride-rich, acidic environment that stabilizes reactive intermediates and enables ligand-to-metal charge transfer (LMCT). Photochemical activation produces mixed-valent titanium species and reactive oxygen intermediates that drive the reduction of atmospheric CO2, initially captured as carbonate and bicarbonate species, to a persistent formaldehyde (C1) intermediate. This intermediate is retained within the coordination sphere and serves as a universal entry point for carbon growth.
A key principle of the framework is ligand-directed divergence: the identity and coordination mode of the ligand determine the fate of the C1 pool. Systems based on 1,10-phenanthroline favor acetal polymerization to polyoxymethylene (POM), while other heteroaromatic ligands promote aldol-type C–C coupling leading to higher oxygenated hydrocarbons. The resulting chemistry is best described not as a closed catalytic cycle but as a non-equilibrium, population-based network in which function emerges from the interaction of multiple interconverting species.
This approach establishes a pathway toward autonomous, low-energy carbon capture and utilization that integrates capture and conversion in a single material platform. By operating under ambient conditions without applied bias or sacrificial reagents, ligand-directed titanium ensembles offer a scalable and potentially transformative route toward sustainable carbon management and the generation of value-added products, directly addressing the goals of reliability, affordability, and sustainability in future energy systems.
