Covalent organic frameworks/carbon nanotubes composite with cobalt(II)pyrimidine sites for bifunctional oxygen electrocatalysis

With characteristics and advantages of functional composite materials, they are commendably adopted in numerous fields especially in oxygen electrocatalysis, which is due to the significant synergies between various components. Herein, a novel bifunctional oxygen electrocatalyst（Co-CNT@COF-Pyr） has been synthesized through in-situ growth of covalent organic frameworks（COFs） layers on the outer surface of highly conductive carbon nanotubes（CNTs） followed by coordination with Co（II）. For electrocatalytic OER, Co-CNT@COF-Pyr reveals a low overpotential（438 mV） in alkaline electrolyte（1.0 M aqueous solution of KOH） with a current density of 10 mA cm-2, which is comparable to most discovered COF-based catalysts. For electrocatalytic ORR, CoCNT@COF-Pyr exhibits a low H2O2 yield range（9.0 %–10.1 %） and a reaction pathway close to 4e-（n =3.82–3.80） in alkaline electrolyte（0.1 M aqueous solution of KOH） within the test potential range of 0.1–0.6 V vs.RHE, which is superior to most reported COF-based catalysts. Hence, this research could not only offer an innovative insight into the construction of composites, but also facilitate the practical application of renewable fuel cells, closed water cycle, and rechargeable metal-air batteries.