Metal- and Pyrolysis-Free Ionic Covalent Organic Framework Nanosheet for Efficient Oxygen Evolution Reaction

Metal-free electrocatalysts for oxygen evolution reaction (OER) are crucial to enable practical water splitting for future clean energy production. The preparation of such electrocatalysts remains a great challenge because they are difficult to obtain a high energy input due to the limitations of kinetically sluggish anodic half-cell reaction. Herein, we develop a novel metal- and pyrolysis-free ionic covalent organic framework (COF) nanosheet (termed JUC-627-NS) and explore its application as an efficient OER electrocatalyst for the first time. Remarkably, the samples combined with JUC-627-NS and graphene can obtain an ultralow overpotential (275 mV at a current density of 10 mA cm-2), which is one of the best among metal- and pyrolysis-free electrocatalysts reported so far. Combining theoretical calculations and in-situ infrared spectroscopy, it is proved that the imidazolium salt moiety is the active center of the electrocatalyst, and the strong cation-π interaction in the complex greatly promotes the reactivity. These results therefore provide a new strategy for designing ionic COF nanosheets as efficient metal-free OER electrocatalysts for energy conversion and storage devices.