Covalent organic framework-derived C@COF core-shell microspheres for electrocatalytic hydrogen evolution

Abstract

Although hydrogen represents a vital source of clean energy, the development of cost-effective, durable materials for use as catalysts in the hydrogen evolution reaction (HER) remains a challenge. In this work, covalent organic framework (COF) - derived core-shell microspheres were prepared as novel electrocatalysts. The previously prepared COF microspheres were pyrolyzed into nitrogen-doped porous carbon (N–C) as the core for enhanced electrocatalytic conductivity. With the assistance of a dual-ligand, the COF shell grew on the surface of N–C to form a core-shell microsphere, which was named N–C@COF. The surface morphology and core-shell structure of N–C@COF were characterized by SEM and TEM. FT-IR, TGA, and XPS were utilized to ascertain the synthesis of COF and the composition of the core-shell microspheres. The N–C@COF core-shell microspheres exhibited excellent HER performance in 1 M KOH electrolyte, demonstrating a low overpotential of 104 mV @ 10 mA cm−2, significantly outperforming pure COF and N–C. Furthermore, the N–C@COF demonstrated excellent HER stability over a 24 h period and retained its HER activity following 2000 consecutive cycles of electrolysis. The presence of the N–C core in the N–C@COF enhanced the electrical conductivity of the catalyst, while the COF shell provided abundant active sites for the HER, resulting in a synergistic improvement in the catalytic efficiency. This work presents a straightforward strategy for synthesizing COF-based multicomponent core-shell microspheres, which provides a promising pathway for the development of available and cost-effective electrocatalysts.