Insights in the Oxygen Reduction Reaction: From Metallic Electrocatalysts to Diporphyrins
Insights in the Oxygen Reduction Reaction: From Metallic Electrocatalysts to Diporphyrins
In the past decade, the mass activity of catalysts for the oxygen reduction reaction (ORR) has been improved mainly via increasing the number of active sites. However, little progress has been made on the improvement of the intrinsic activity of ORR catalysts; consequently, the widespread use of fuel cells is still limited by low energy efficiency. In this Perspective, we provide an overview of the fundamentals underlying the ORR on platinum-based catalysts as well as metal–nitrogen–carbon nonprecious metal catalysts. We also report the diporphyrin complexes as promising catalysts with outstanding activity owing to structural advantages. In particular, diporphyrin anthracene (DPA) with optimized ligand coordination has a low barrier to dissociate O2 molecules at the optimal oxygen adsorption energy region, which might unlock overpotentials of less than 0.2 V.