Exploring Counter Anions in a Redox-Active Viologen-Based Ionic Porous Organic Polymer (iPOP) for Selective Reduction of Oxygen to H₂O₂

Hydrogen peroxide, an environmentally friendly oxidant, is in high demand in various industrial sectors. Electrochemical H2O2 production by 2e– reduction of O2 is a suitable and greener alternative to the traditional anthraquinone process. However, developing metal-free electrocatalysts that predominantly follow the 2e– reduction process over the more favorable 4e– reduction is challenging. Here, we report a viologen-based redox-active ionic porous organic polymer (iPOP-TAPA-Cl) toward selective production of H2O2 (86%) electrocatalytically. By varying the counteranion (Cl–) with other halogen anions (F–, Br–, and I–), a maximum H2O2 selectivity of 98.5% with exceptional current efficiency was achieved in the case of iPOP-TAPA-F.