Boosting Photocatalytic Performance of MOF‐on‐MOF Heterostructures by Constructing Rigid Charge Channels

The control of the composition of secondary building units (SBUs) in Metalorganic frameworks (MOF) and the preparation of MOF single crystals are challenging. In this study, two MOF single crystals, Co‐TBAPy(EF) and Co‐MIL‐53(NH 2 ) are successfully prepared for the first time. The aqueous phase modulation results in a novel structure for both MOF, and they have similar SBUs. Co‐MIL‐53(NH 2 ) is grown epitaxially on Co‐TBAPy(EF) via SBUs and formed Co‐MIL‐53(NH 2 )/Co‐TBAPy(EF) heterostructures, which not only integrate the advantages of the two MOF, but also chemically link interfacial channels, facilitate rapid electron transfer. Experimental results and theoretical calculations confirm that the built‐in electric field at the interface accelerated the charge transfer. This study provides insights into the construction of MOF single crystals, the modulation of SBUs, and the design of MOF‐on‐MOF heterostructures.