Modulating Pore Sizes and Electronic Properties of Covalent Organic Polymers for the Catalysis of Two-Electron Oxygen Reduction Reaction in Neutral Media

Covalent organic polymers (COPs) have been used as electrocatalysts to produce hydrogen peroxide (H 2 O 2 ) via a two-electron oxygen reduction reaction (2e – ORR). However, performing the 2e – ORR catalysis under neutral conditions remains a challenge due to the lack of suitable catalytic sites and porosity. Herein, we adopted a modulating synthetic strategy to tailor the pore sizes and electronic properties and thus obtained a highly selective and active COP catalyst for the 2e – ORR in a neutral medium. By modifying the linkers, the pore size of the COPs ranged from 0.49 to 0.87 nm, and the electronic state of the Cr centers also changed. Cr-TCNE-COP, a COP with tetracyanoethylene linkers, showed high H 2 O 2 selectivity (95.3%) with a mass activity of 398.2 A g –1 at a potential of 0 V vs RHE, which was 1.6 times higher than that of the COP with pyromellitic dianhydride linkers, Cr-PMDA-COP. The results indicate that a shorter carbon matrix adjacent to the Cr active sites favored the adsorption of O 2 and desorption of *OOH. This study opens the road for efficient H 2 O 2 electroproduction in neutral media by synergistically manipulating the reaction pore microenvironment and electronic state.