Microenvironment Regulation of {(Co4O4)-O-II} 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, Rux-Eu-bpdc, and Rux-Eu-bpydc) with different surrounding confined spaces were designed and synthesized. These photosensitizing Rux-Eu-MOFs were used as the molecular platform to encapsulate the [Co-4(II)(dpy{OH}O)(4)(OAc)(2)(H2O)(2)](2+) (Co-4) cubane cluster for constructing Co-4@Rux-Eu-MOF (x = 0.1, 0.2, and 0.4) heterogeneous photocatalysts for efficient CO2 photoreduction and water splitting. The H-2 and CO yields can reach 446.6 and 459.8 mu mol.g(-1), respectively, in 10 h with Co4@Ru0.1-Eu-bpdc as the catalyst, and their total yield can be dramatically improved to 2500 mu mol. 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 CO2 photoreduction and water splitting.