Electrocatalytic oxygen reduction reaction promoted by titanium-based tetrapyrazinoporphyrazines

In this study, we unveiled titanium-based tetrapyrazinoporphyrazines as a valuable alternative to noble metals in the oxygen reduction reaction (ORR). By simply modifying the synthetic conditions, we were able to tune the ORR selectivity while showing that the introduction of substituents on the macrocycle periphery is detrimental to the ability of the complex to reduce molecular oxygen. A complete electrochemical characterization in different conditions is reported together with rotating ring-disk electrode measurements, which assessed the possibility of selectively switching from 2- to a 4-electron reduction product changing the titanium precursor amounts during the complex synthesis.