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 π–d conjugated two-dimensional (2D) MOF Co3(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-N4 sites (23.44 wt. % of Co element). Co3(HITP)2 exhibits high electrical conducting behavior (1150 S m−1), outperforming holey graphene (∼1000 S m−1). DFT theoretical calculation verifies the metallic behavior of Co3(HITP)2 and demonstrates that the π–d conjugation contributes to the excellent conductivity. Additionally, Co3(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 π–d conjugated 2D MOFs as electrocatalysts.