Charge-Transfer-Regulated Selective Solar Fuel Production in Aqueous Medium by a Tetrathiafulvalene-Based Redox-Active Metal-Organic Framework

Developinga suitable photocatalyst for artificial photosynthesisis a challenging and highly relevant assignment in contemporary researchrelated to energy and environment. Here, we report photocatalyticCO(2) reduction in aqueous medium under visible light bya conducting Zn (II) MOF, Zn-TTF-MOF synthesized by using a redoxactive tetrathiafulvalenetetracarboxylate linker. Zn-TTF-MOF displaysan intramolecular charge-transfer (intra-CT) band from TTF to theZn(II)-coordinated benzenecarboxylate unit in visible light with aoptical band gap of 1.83 eV. Under visible light, Zn-TTF-MOF enablesthe production of 784.4 & mu;mol g(-1) CO in 10h from CO2 in water with a selectivity of & SIM;94% withoutadditional sacrificial electron donor, cocatalyst, or exterior photosensitizer.The low exciton binding energy results in efficient charge separationin the MOF, as realized by the transient photocurrent and electrochemicalimpedance spectroscopy measurement under light irradiation. Finally,a plausible CO2 reduction mechanism is derived based onan in situ diffuse-reflectance infrared Fourier transformstudy (DRIFTS) followed by DFT calculations.

Automated summary

Developing a suitable photocatalyst for artificial photosynthesis is a challenging task in contemporary research on energy and environment. This study reports the photocatalytic CO2 reduction in aqueous medium under visible light using a conducting Zn(II) MOF, Zn-TTF-MOF, which is synthesized using a redox active tetrathiafulvalene tetracarboxylate linker. The Zn-TTF-MOF exhibits efficient charge separation and enables the production of CO with high selectivity, under visible light, without the need for additional sacrificial electron donor or cocatalyst.