An Initial Covalent Organic Polymer with Closed-F Edges Directly for Proton-Exchange-Membrane Fuel Cells.

Covalent organic polymers (COPs) are a class of rising electrocatalysts for the oxygen reduction reaction (ORR) due to the atomically metrical control of the organic molecular components along with highly architectural robustness and thermodynamic stability even in acid or alkaline media. However, the direct application of pristine COPs as acidic ORR electrocatalysts, especially in device manner, e.g., in proton-exchange-membrane fuel cells (PEMFCs), remains a big challenge. Currently, the decoration toward electronic structures of active sites is considered a vital pathway to enhancing the acidic ORR activity of carbon-based electrocatalysts. Here, an initial F-decorated fully closed π-conjugated quasi-phthalocyanine COP (denoted as COP -F) is reported. The introduction of the closed-F edges stepwise drags more electrons from FeN sites in COP -F into the catalyst margin, which weakens the occupied numbers of bonding orbitals between COP -F and OH* intermediates at the rate-determining step, exhibiting over five times intrinsic performance beyond the counterpart without F functionalities (termed as COP ). Significantly, the maximum power density utilizing COP -F as a cathode catalyst in PEMFCs is remarkably increased by an order of magnitude compared with COP , which is a stride forward among catalysts based on a pyrolysis-free conjugated-polymer network in device manner to date.