Chemically Exfoliated Semiconducting Bimetallic Porphyrinylphosphonate Metal-Organic Layers for Photocatalytic CO2 Reduction under Visible Light

In this paper, we report the first example of semiconducting porphyrinylphosphonate metal-organic framework (MOF) [Co(Ni-H7TPPP)(2)]center dot 8H(2)O and its chemical exfoliation into ultrathin metal-organic layers (MOLs) with an electric conductivity up to 0.12 S cm(-1) at RT. Benefiting from the 2D layered structure possessing highly accessible metalloporphyrin-active motifs, a negatively charged surface, and a phosphonate-enhanced structural stability, the exfoliated MOL enables the material to behave as an efficient cocatalyst in coordination with positively charged [Ru(bpy)(3)](2+) to photocatalytically reduce CO2 to CO in a high yield rate (3.16 x 10(4) mu mol g(-1) h(-1)) and selectivity (81%). Spectroscopic studies engaging DRS, UPS, PL, EIS, and TPR unanimously point to the remarkable photocatalytic performance being a result of proper band alignment among the system components and great charge extraction capability of the cocatalyst. More importantly, by explicitly dissecting the band structure and charge transport behavior, this study provides insights into catalyst design to afford a coherent energy flow in hybrid photocatalytic systems.

Automated summary

This paper presents the first example of a semiconducting porphyrinylphosphonate metal-organic framework and its chemical exfoliation into ultrathin metal-organic layers with high conductivity and efficient photocatalytic properties in reducing CO2 to CO. Spectroscopic studies suggest that the remarkable photocatalytic performance is a result of proper band alignment and great charge extraction capability of the cocatalyst, providing insights into catalyst design for coherent energy flow in hybrid photocatalytic systems.