Boosting hydrogen peroxide production via establishment and reconstruction of single-metal sites in covalent organic frameworks

Covalent organic frameworks (COFs) have been well developed in electrocatalytic systems owing to their controllable skeletons, porosities, and functions. However, the catalytic process in COFs remains underexplored, hindering an in-depth understanding of the catalytic mechanism. In this work, uniform Pt-N1O1Cl4 sites chelated via C-N and C=O bonds along the one-dimensional and open channels of TP-TTA-COF were established. Different from conventional single-metal sites constructed for the near-free platinum for hydrogen evolution, the as-constructed PtCl-COF showed 2e(-) oxygen reduction for H2O2 production. We tracked the dynamic evolution process of atomic Pt sites in which Pt-N1O1Cl4 was transformed into Pt-N1O1(OH)(2) using in situ X-ray adsorption. The theoretical calculations revealed that the strong Pt-support interaction in Pt-N1O1(OH)(2) facilitated *OOH formation and thus led to higher selectivity and activity for the oxygen reduction reaction in the 2e(-) pathway. This work can expand the applications of COFs through the regulation of their local electronic states for the manipulation of the metal center.