The development of upscalable oxygen
evolving electrocatalysts from earth-abundant metals able to operate
in neutral or acidic environments and low overpotentials remains a
fundamental challenge for the realization of artificial photosynthesis.
In this study, we report a highly active phase of heterobimetallic
cyanide-bridged electrocatalysts able to promote water oxidation under
neutral, basic (pH < 13), and acidic conditions (pH > 1). Cobalt–iron
Prussian blue-type thin films, formed by chemical etching of Co(OH)1.0(CO3)0.5·nH2O nanocrystals, yield a dramatic enhancement of the catalytic
performance toward oxygen production, when compared with previous
reports for analogous materials. Electrochemical, spectroscopic, and
structural studies confirm the excellent performance, stability, and
corrosion resistance, even when compared with state-of-the-art metal
oxide catalysts under moderate overpotentials and in a remarkably
large pH range, including acid media where most cost-effective water
oxidation catalysts are not useful. The origin of the superior electrocatalytic
activity toward water oxidation appears to be in the optimized interfacial
matching between catalyst and electrode surface obtained through this
fabrication method.