Water Oxidation Performance Enhanced by Electrochemically Designed Vacancies on a Prussian Blue Catalyst

Prussian blue analogues are one of the most promising examples of water oxidation catalysts presenting great performance, activity, and stability under mild conditions. Herein, we report an alternative methodology to synthesize the Prussian blue, obtaining a catalyst with vacancies created by an electrochemical method. This catalyst showed an outstanding activity, with an onset overpotential of 361 mV. Using pyridine as a molecular probe, we identified the presence of vacant Fe2+ sites, and the quantification of these sites allowed us to estimate a TOF number of 0.2170 s–1 for the water oxidation reaction. These results indicate that defect engineering is a versatile strategy to boost the catalytic activity in Prussian blue analogues by increasing the number of active sites.