Encapsulating a Co(II) Molecular Photocatalyst in Metal-Organic Framework for Visible-Light-Driven H2 Production: Boosting Catalytic Efficiency via Spatial Charge Separation

The photodriven H-2 generation from water splitting, providing a high-performance energy source, has been recognized to be a promising pathway for solar energy conversion. However, the efficient charge separation for photocatalysts remains a critical issue. In this work, we have rationally encapsulated a Co(II) molecular photcatalyst, [Co-II(TPA)CI][CI] (TPA = tris(2-pyridylmethyl)-amine), inside the cages of a metal organic framework (MOF) photosensitizer, MIL-125-NH2, for visible-light-driven H-2 production. This noble-metal-free composite photocatalyst facilitates the photo induced charge transfer from MIL-125-NH2 to the Co(II) complex and greatly improves the spatial charge separation, thus significantly boosting the photocatalytic efficiency of H-2 production. In addition, MIL-125-NH2 behaves as a host matrix to achieve hetrogenization of the Co(II) complex, and thus, the composite can be well-recycled.