Decoration of Metal-Organic Frameworks with Coenzyme Mimics for Boosting Photocatalytic Hydrogen Production

Despite remarkable progress achieved in biomimetic catalysis, the majority of studies have primarily concentrated on mimicking the structures of catalytic sites in metalloenzymes, while frequently neglecting the crucial roles of multifunctional coenzymes therein. In this study, the coenzyme mimics of nicotinic acid (NA) and 3-carboxy-1-methylpyridinium iodide (NA-Me, simply denoted as NM) have been modified onto the metal-organic framework UiO-66-NH₂, affording UiO-66-X (X═NA, NM) with varying the degree of mimicry for the nicotinamide nucleotide coenzyme. Remarkably, UiO-66-NM showcases approximately five- and seven-fold activity higher than UiO-66-NA and the pristine UiO-66-NH₂, respectively, in the photocatalytic hydrogen production. Both experimental and computational results reveal that the NM dangling on the MOF undergoes structural redox change similar to that in the regeneration process of NAD(P)H coenzyme, which serves as the proton and electron relays surrounding catalytic Pt sites, facilitating proton-coupled electron transfer (PCET) and thereby boosting photocatalytic activity. This work offers new insights and strategies for the design and fabrication of biomimetic heterogeneous catalysts.