Electronic and catalytic engineering in two-dimensional vdW metal-organic frameworks through alloying

Bimetallic metal-organic framework (MOFs) alloys, in which heterogeneous metal clusters are incorporated into their backbone, are capable of highly selective separations and catalysis. Due to limitations in our fundamental understanding of their alloying, however, established methods result in phase-separated or amorphous two-dimensional (2D) MOFs or lack precise control over alloy ratios. Here, our results demonstrate 2D MOF alloys where metal cation ratios (M-1 and M-2) in (MxM1-xBDC)-M-1-B-2 (M-1 or M-2= Zn, Cu, Ni, Co, Fe, Mn) can be engineered on demand by controlling the metal salt dissociation constants. Resulting MOF alloys exhibit a highly 2D nature with excellent crystallinity and minute control over metal cation ratios. Our experimental and theoretical results show that their electronic bandgaps and photoexcited carrier lifetimes can be engineered by metal cation alloying. Interestingly, 2D alloyed MOFs enable high-efficiency photo-catalytic water reduction performance in Co/Ni MOF alloys owing to the spatially separated metal clusters in 2D MOF alloys.