Cobalt-Atom Active\nSites Grafted UiO-66-NH<sub>2</sub> via EDTA for the Enhanced Production\nof Syngas in CO<sub>2</sub> Photoreduction

In recent years, the use of photocatalysts has emerged\nas a promising\nresearch direction to transform harmful CO<sub>2</sub> molecules into\nrenewable fuels. In this work, the chelating agent ethylenediaminetetraacetic\nacid (EDTA) containing a central metal atom like Co was attached to\nthe UiO-66-NH<sub>2</sub> metal–organic frameworks (MOFs) through\na one-pot synthesis. Several samples with different molar ratios of\nUiO-66-NH<sub>2</sub>–Co and EDTA (molar ratios of UiO-66-NH<sub>2</sub>–Co/EDTA is 1.2; 0.6; and 0.4) were synthesized and\nassessed for photocatalytic CO<sub>2</sub> reduction to produce syngas\n(the mixture of CO and H<sub>2</sub>), which can be used for generating\nliquid fuels. Among these samples, the highest syngas production rate\nwas achieved by sample U-E-0.6, yielding around 776.40 and 1217.29\nμmol g<sup>–1</sup> h<sup>–1</sup> of CO and H<sub>2</sub>, respectively, at the end of 4 h. Multiple investigations,\nincluding electrochemical impedance, time-resolved, steady state photoluminescence,\nlinear sweep voltammetry, and photocurrent measurements, revealed\nthat the addition of EDTA-metal to UiO-66-NH<sub>2</sub> improved\nthe photoelectrochemical properties of the system, thereby enhancing\nits photocatalytic activity under solar irradiation. This research\npaves the way for the development of a single atom encapsulated in\nthe MOF material for photocatalytic CO<sub>2</sub> reduction.