A simple defect engineering approach to systematically tune the band gap of the prototypical zirconium-based metal–organic framework UiO-66 is reported. Defect engineered materials display enhanced photocatalytic activity.

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO₂ reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

The design of robust, high-performance photocatalysts is key for the success of solar fuel production <i>via</i> CO₂conversion. Herein, we present hypercrosslinked polymer (HCP) photocatalysts for the selective reduction of CO₂ to CO, combining excellent CO₂ sorption capacities, good general stabilities, and low production costs. HCPs are active photocatalysts in the visible light range, significantly out-performing the benchmark material, TiO₂ P25, using only sacrificial H₂O. We hypothesise that superior H₂O adsorption capacities led to concentration at photoactive sites, improving photocatalytic conversion rates when compared to sacrificial H₂. These polymers are an intriguing set of organic photocatalysts, displaying no long-range order or extended pi-conjugation. The as-synthesised networks are the sole photocatalytic component, requiring no co-catalyst doping or photosensitiser, representing a highly versatile and exciting platform for solar-energy conversion.

We report a defect-engineering approach to modulate the band gap of zirconium-based metal-organic framework UiO-66, enabled by grafting of a range of amino-functionalised benzoic acids at defective sites. Defect engineered MOFs were obtained by both post-synthetic exchange and modulated synthesis, featuring band gap in the 4.1-3.3 eV range. Ab-initio calculations suggest that shrinking of the band gap is mainly due to an upward shift of the valence band energy, as a result of the presence of light-absorbing monocarboxylates. The photocatalytic properties of defect-engineered MOFs towards CO₂ reduction to CO in the gas phase and degradation of Rhodamine B in water were tested, observing improved activity in both cases, in comparison to a defective UiO-66 bearing formic acid as the defect-compensating species.

The design of robust, high-performance photocatalysts is key for the success of solar fuel production <i>via</i> CO₂conversion. Herein, we present hypercrosslinked polymer (HCP) photocatalysts for the selective reduction of CO₂ to CO, combining excellent CO₂ sorption capacities, good general stabilities, and low production costs. HCPs are active photocatalysts in the visible light range, significantly out-performing the benchmark material, TiO₂ P25, using only sacrificial H₂O. We hypothesise that superior H₂O adsorption capacities led to concentration at photoactive sites, improving photocatalytic conversion rates when compared to sacrificial H₂. These polymers are an intriguing set of organic photocatalysts, displaying no long-range order or extended pi-conjugation. The as-synthesised networks are the sole photocatalytic component, requiring no co-catalyst doping or photosensitiser, representing a highly versatile and exciting platform for solar-energy conversion.