Three‐in‐One Spacer Strategy Toward Highly Alkali‐Resistant Covalent Organic Frameworks for Efficient Oxygen Evolution Reaction in Alkaline Seawater

ABSTRACT Molecular catalysts with well‐defined active sites and structural tunability are proposed as promising electrocatalysts for alkaline oxygen evolution reaction (OER). However, poor alkaline resistance, low atomic utilization, limited mass transfer resulted in rapid activity degradation and unstable catalytic performance of molecular catalysts in alkaline environments. Herein, a three‐in‐one spacer strategy was designed to develop highly alkali‐resistant phthalocyanine‐based covalent organic frameworks (COFs) by integrating a spacer with hydrophilic groups and stable piperazine linkages in skeletons, which endows COF with high alkaline resistance, high atomic utilization and effective mass transfer. As a result, the COF shows a surprising activity with an ultra‐low overpotential of 77 mV and a long‐term durability of exceeding 290 h at 500 mA cm −2 in 6 M KOH and seawater at 80°C in an anion exchange membrane electrolyzer. To the best of our knowledge, the unprecedented stability and activity exceeds all organic catalysts. Theoretical and experimental studies reveal that the hydrophilic units not only increase the mass transfer, but also can facilitate the *OH deprotonation on the Co sites, which further improve the catalytic activity.