Co3(hexaiminotriphenylene)2: A conductive two-dimensional π-d conjugated metal-organic framework for highly efficient oxygen evolution reaction

The application of metal-organic frameworks (MOFs) in electrocatalysis is mainly limited by their poor electrical conductivity. Herein, we report an intrinsically conductive pi-d conjugated two-dimensional (2D) MOF Co-3(HITP)(2) (HITP= 2,3,6,7,10,11-hexaiminotriphenylene), which possesses well-defined porous networks and much larger number of active sites for oxygen evolution, i.e. Co-N-4 sites (23.44 wt. % of Co element). Co-3(HITP)(2) exhibits high electrical conducting behavior (1150 S m(-1)), outperforming holey graphene (similar to 1000 S m(-1)). DFT theoretical calculation verifies the metallic behavior of Co-3(HITP)(2) and demonstrates that the pi-d conjugation contributes to the excellent conductivity. Additionally, Co-3(HITP)(2) displays prominent oxygen evolution reaction (OER) activity (an overpotential of 254 mV vs. RHE at a current density of 10 mA cm(-2) and a Tafel slope of 86.5 mV dec(-1)) in alkaline electrolyte, which is comparable or even superior to most cobalt-based materials reported thus far as well as commercial RuO2 and IrO2. These promising results suggest the great potential of pristine pi-d conjugated 2D MOFs as electrocatalysts.