Synthesis and electrocatalysis of ordered carbonaceous frameworks from Ni porphyrin with four ethynyl groups

Ordered carbonaceous frameworks (OCFs) are carbon materials possessing three-dimensional ordered structures with regularly-aligned single-atomic metal species. OCFs are characterized by well-defined chemical structures like organic-based frameworks together with high thermal/chemical stability and electrical conductivity, making them an interesting platform for electrocatalytic applications. OCFs are synthesized by a simple thermal treat-ment of metalloporphyrin crystals with polymerizable moieties, but the reported precursors have been limited to only four types. Herein, we report two new types of Ni porphyrin precursors which can be converted into OCFs. The comprehensive structural analysis of resulting OCFs, including PXRD, TEM, HAADF-STEM, Ni K-edge XAFS and N2 adsorption measurement, demonstrated that Ni-N4 coordination units, namely single-atomic Ni sites, are regularly immobilized in the microporous carbon framework. There is a general tendency in which the higher the number of ethynyl moieties, the more the microporosity developed in the resulting OCFs. Furthermore, single-atomic Ni species catalyze electrochemical hydrogen evolution reaction even without any conductive additives.

Automated summary

Ordered carbonaceous frameworks (OCFs) are carbon materials with three-dimensional ordered structures and regularly-aligned single-atomic metal species. OCFs have well-defined chemical structures like organic-based frameworks, high thermal/chemical stability, and electrical conductivity, making them an interesting platform for electrocatalytic applications. We report two new types of Ni porphyrin precursors that can be converted into OCFs. The structural analysis of resulting OCFs shows regularly immobilized single-atomic Ni sites in the microporous carbon framework. The number of ethynyl moieties affects the microporosity of resulting OCFs, and single-atomic Ni species can catalyze electrochemical hydrogen evolution reaction without any conductive additives.