Metal-organic aerogels based on titanium(IV) for visible-light conducted CO2 photoreduction to alcohols

Metal-organic frameworks (MOFs) imply an appealing source of photocatalysts, as they combine porosity with tailorable electronic properties and surface chemistry. Herein we report a series of unprecedented metal-organic aerogels (MOAs) comprised by Ti(IV) oxo-clusters and aromatic dicarboxylic linkers as an alternative to microporous MIL-125 and MIL-125-NH 2 MOFs. Discrete titanium oxo-clusters polymerized upon the addition of the dicarboxylic linkers to give rise to a metal-organic gel. Their supercritical drying led to aerogels comprised by nanoscopic particles ( ca . 5–10 nm) cross-linked into a meso/macroporous microstructure with surface area ranging from 453 to 617 m 2 ·g –1 , which are comparatively lower than the surface area of the microporous counterparts (1336 and 1145 m 2 ·g –1 , respectively). However, the meso/macroporous microstructure of MOAs can provide a more fluent diffusion of reagents and products than the intrinsic porosity of MOFs, whose narrower channels are expected to imply a more sluggish mass transport. In fact, the assessment of the continuous visible-light driven photocatalytic CO 2 reduction into methanol shows that MOAs (221–786 μmol·g –1 ·h –1 ) far exceed the performance of their microporous counterparts (49–65 μmol·g –1 ·h –1 ), but also surpass the production rates provided by up-to-date reported photocatalysts. • Novel metal-organic aerogels based on titanium(IV) are presented. • These materials photocatalyse CO2 conversion under visible-light illumination. • The methanol production rates surpass up-to-date reported photocatalysts.