Abstract
Optimizing molecular structures in oxygen reduction reaction (ORR) is crucial for enhancing catalytic efficiency and stability, particularly with respect to the effective adsorption and conversion of reaction intermediates. Sulfur-containing heterocyclic compound thiophene can precisely modulate the electronic states and local charge densities, thereby fine-tuning the adsorption and reactivity of microporous polymers, yet, it remains a largely unexplored area. Herein, thiophene-based building blocks featuring diversified linkers into a phenyl-containing model Ph-CMP are developed, affording the thiophene-fused BPT-CMP and the thiophene-linked BCT-CMP. The electron density and adsorption capacity of the frameworks are well regulated through condensation and connecting modification, showing excellent half-wave potentials compared to the reversible hydrogen electrode, surpassing even most metal-free polymer electrocatalysts. Through theoretical calculations and experimental results, we have validated that the thiophene-fused skeleton (BPT-CMP) triggers the activation of thiophene units, with the exposed pentatomic heterocyclic carbon atom (site-3) serving as the catalytic active site.