Interface engineering for modulating catalytic selectivity of covalent organic frameworks for oxygen reduction

Covalent organic frameworks (COFs) have shown various applications in electrocatalytic systems because of their designable skeletons, controllable porosities and excellent stability. Nevertheless, their poor conductivity resulted in limited activity and selectivity, and one of the most important strategies was mixing the COFs with conductive carbons. However, the electronic synergism between the active COFs and conductive substrate is still underexplored. Herein, we have first demonstrated the electronic synergism of catalytic COF and carbon substrate by constructing a hetero-interface toward ORR. The interface engineering of COFs achieved the turnover frequency (TOF) increases by two orders of magnitude and improved the half-wave potential to 0.79 V and limited current density to 5.5 mA cm−2. Additionally, the formation interface not only facilitates the electron transfer from substrate to the COF but also tunes the electronic properties of the COF. The electron modification of active sites changed the oxygen reduction from 2e− to 4e− pathway. This work provides us with a new insight in designing COFs for electrocatalysis.