Balance and Optimization of Oxygen Reduction Reaction Pathways on Hydroxyl‐containing Conjugated Microporous Polymers for Improved Hydrogen Peroxide Photogeneration

ABSTRACT The conjugated microporous polymers (CMPs) represent a promising emerging class of organic semiconductor photocatalyst for hydrogen peroxide (H 2 O 2 ) photosynthesis. However, most CMPs exhibit broad bandgaps, insufficient O 2 adsorption sites, and limited molecular polarity, these inherent limitations hinder light absorption, inhibit O 2 adsorption, and suppress charge transport of the CMPs, consequently reducing their H 2 O 2 generation performance. In this work, we have employed a “building block functionalization” strategy to synthesize a series of CMPs with varying numbers of hydroxyl groups (CMP‐xOH, x = 0, 1, 2, 3, representing the number of hydroxyl groups in a repeating unit) through precise molecular design. The experimental results demonstrate that the introduction of hydroxyl groups narrows the bandgap, enhances the O 2 adsorption, improves the charge transfer, and more significantly, balances and optimizes the oxygen reduction reaction (ORR) pathways. The most efficient catalyst, CMP‐3OH, achieves an optimal balance between the kinetically favorable stepwise indirect 2e − ORR pathway and the thermodynamically favorable direct 2e − ORR pathway, consequently attaining a H 2 O 2 generation rate of 6.75 mmol g −1 h −1 in air and pure water under a neutral condition. This work provides a new insight into the investigation on the structure‐performance relationship in photocatalytic activity of hydroxyl‐containing CMPs.