Metalation-Induced Triazine-Based Covalent Organic Framework as a High Performance Electrocatalyst for Oxygen and Hydrogen Evolution Reactions

Abstract

The pursuit of efficient and functionalized covalent organic framework (COF) nanomaterials holds significant importance given their potential applications across various fields. Notably, their relevance extends to the sustainable production of hydrogen, a promising future fuel, through water electrolysis. A βketamine-functionalized COF was prepared using Schiff base condensation of 1,3,5-triformylphloroglucinol and 1,3,5-tris(4aminophenyl)triazine. The as-prepared β-ketamine-linked COF was chosen as the precursor for the postsynthetic modification, where the β-ketamine moieties were effectively coordinated with metal ions such as nickel (Ni), cobalt (Co), and iron (Fe), resulting in functional metal-coordinated COF complexes designated as Ni-COF, Co-COF, and Fe-COF, respectively, and their electrocatalytic activity toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was systematically investigated. The ensuing Ni-COF demonstrates significantly greater activity toward OER and HER compared to Co-COF and Fe-COF. For HER, in a 0.5 M H 2 SO 4 solution, Ni-COF requires an overpotential of 208 mV to achieve a 10 mA cm −2 current density. For OER, Ni-COF demands an overpotential of 302 mV to reach the same current density in 1 M KOH solution, surpassing the state-of-the-art OER catalyst, RuO 2 , which required a 370 mV overpotential to attain the same current density. Also, the turnover frequency increases approximately 5 times in Ni-COF compared to the bare material. Moreover, the electrocatalyst exhibited excellent stability for 24 h for both HER and OER, demonstrating its superiority toward these reactions. This study underscores the potential of metalationinduced COF-based materials for applications in sustainable hydrogen production through HER and OER processes.