(173s) Photoelectrochemical Reduction of Oxygen on Two-Dimensional Covalent Organic Frameworks

Porphyrinoids are promising materials that have become the subject of much interest in the field of photocatalytic research. In nature, prophyrinoids are the basis for energy generation. They catalyze photosynthesis in plants and cellular respiration in animals. All porphyrinoids contain a tetrapyrrole porphyrin structure, which mirrors the photosynthetic reaction center of chlorophyll. Evolution has deemed this molecular structure the most efficient in converting solar energy into chemical potential energy. Among the porphyrinoids family, porphyrin-based materials are emerging due to their ease of synthetic pathway and functionalization. Polymerization of porphyrins to create covalent organic frameworks (COFs) and networks increases the stability of these materials. Herein, we utilize a vapor phase pathway to deposit thin-films of polymeric materials containing porphyrin-based COFs. The as-synthesized material was employed as a photoelectrocatalyst for oxygen reduction reactions and illuminated under visible light while placed in a basic solution saturated with oxygen. The result was a 50% improvement in cathodic current under illumination, and a shift in the onset potential of reduction, suggesting a shift in the flat band potential of the COFs as a result of the accumulation of photogenerated carriers in the polymeric network. The balance between the ion transfer and the charge transfer enables us to record the dynamics of photo-to-fuel conversion in ORR. The materials were further processed and the coating was utilized as a precursor for creating conductive electrodes hosting single-atom catalysts. We report on the enhanced measured photocatalytic performance and the number of active sites generated via post-processing.