Microenvironment Regulation of {Co 4 II O 4 } Cubane for Syngas Photosynthesis.

It is a great challenging task for selectivity control of both CO 2 photoreduction and water splitting to produce syngas via precise microenvironment regulation. Herein, a series of UiO-type Eu-MOFs (Eu-bpdc, Eu-bpydc, Ru x -Eu-bpdc, and Ru x -Eu-bpydc) with different surrounding confined spaces were designed and synthesized. These photosensitizing Ru x -Eu-MOFs were used as the molecular platform to encapsulate the [Co II 4 (dpy{OH}O) 4 (OAc) 2 (H 2 O) 2 ] 2+ ( Co 4 ) cubane cluster for constructing Co 4 @Ru x -Eu-MOF ( x = 0.1, 0.2, and 0.4) heterogeneous photocatalysts for efficient CO 2 photoreduction and water splitting. The H 2 and CO yields can reach 446.6 and 459.8 μmol·g -1 , respectively, in 10 h with Co 4 @Ru 0.1 -Eu-bpdc as the catalyst, and their total yield can be dramatically improved to 2500 μmol·g -1 with the ratio of CO/H 2 ranging from 1:1 to 1:2 via changing the photosensitizer content in the confined space. By increasing the N content around the cubane, the photocatalytic performance drops sharply in Co 4 @Ru 0.1 -Eu-bpydc, but with an enhanced proportion of CO in the final products. In the homogeneous system, the Co 4 cubane was surrounding with Ru photosensitizers via week interactions, which can drive water splitting into H 2 with >99% selectivity. Comprehensive structure-function analysis highlights the important role of microenvironment regulation in the selectivity control via constructing homogeneous and heterogeneous photocatalytic systems. This work provides a new insight for engineering a catalytic microenvironment of the cubane cluster for selectivity control of CO 2 photoreduction and water splitting.