(765h) Creating Metal-Oxide Interfaces in Metal Organic Framework for Efficient Methanol Synthesis from CO2

Figure 1. (A) Schematic view of the approach for
creating interfaces between metal nanoparticles in 3-D frameworks. (B) The Cu
k-edge XAFS and the fitted spectrum suggesting Cu nanoclusters locate in the
pores of MOF with ~30% Cu-O-Zr interfacial sites. (C) The activity in selective
hydrogenation of CO₂ to methanol suggesting Cu/UiO66 has superior
performance.

Interfaces
between metals and metal oxides have high activity for activation and
conversion of CO₂, whereas they are just accessible on the perimeter
of the metal nanoparticles on traditional supported catalysts. We present here
a strategy for the synthesis of well-defined metal-metal oxide interfaces by
incorporating metal nanoparticles into the pores of metal organic frameworks
(UiO-66 and ZIF-8) (Figure 1A). Pd or Cu nanoparticles bind to the
hydroxyl groups of the secondary building units (SBUs), i.e., Zr₆ oxide
or ZnN₄ clusters (UiO-66 and ZIF-8, respectively). As a result, the
proportion of metal atoms located at the interfaces with the SBUs is maximized
(Cu in UiO-66, Figure 1B). Our novel systems are highly active for the
selective conversion of CO₂ to methanol even compared to commercial
catalysts and highly dispersed metal clusters deposited in zeolites. For
instance, Cu/UiO-66 is more active than the Cu on bulk ZrO₂ and
commercial Cu/ZnO/Al₂O₃ catalyst (Figure 1C). Our
work highlights the advantages of combining the architecture and chemical
features of MOF with small metal entities for CO₂ and H₂
activation.