Tailoring Crystal Facets of Metal-Organic Layers to Enhance Photocatalytic Activity for CO2 Reduction

It is common that different crystal facets in metal and metal oxide nanocrystals display different catalytic performances, whereas such phenomena have been rarely documented in metal-organic frameworks (MOFs). Herein, we demonstrate for the first time that a nickel metal-organic layer (MOL) exposing rich (100) crystal facets (Ni-MOL-100) shows a much higher photocatalytic CO2-to-CO activity than the one exposing rich (010) crystal facets (Ni-MOL-010) and its bulky counterpart (bulky Ni-MOF), with a catalytic activity up to 2.5 and 4.6 times more active than Ni-MOL-010 and bulky Ni-MOF, respectively. Theoretical studies reveal that the two coordinatively unsaturated Ni-II ions with a close distance of 3.50 angstrom on the surface of Ni-MOL-100 enables synergistic catalysis, leading to more favorable energetics in CO2 reduction than that of Ni-MOL-010.

Automated summary

Different crystal facets in metal and metal oxide nanocrystals often exhibit varied catalytic performances, whereas this phenomenon is rarely seen in metal-organic frameworks. A nickel metal-organic layer with rich (100) crystal facets demonstrates significantly higher photocatalytic CO2-to-CO activity compared to the one with rich (010) crystal facets and its bulky counterpart, due to synergistic catalysis on the surface enabling more favorable energetics in CO2 reduction.