Water oxidation is the primary step in both
natural and artificial photosynthesis to convert solar energy in into
chemical fuels. Herein, we report the first cobalt-based
pincer catalyst for electrolytic water oxidation at neutral pH with high efficiency
under electrochemical conditions. Most importantly, ligand (pseudo)aromaticity
is identified to play an important role in the electrocatalysis. A significant
potential jump (~300 mV) was achieved towards a lower positive value when the
aromatized cobalt complex was transformed to a (pseudo)dearomatized cobalt
species. This complex catalyzes the water oxidation in its high valent
oxidation state at a much lower overpotential (~ 340 mV vs. NHE) based on the
onset potential (0.5 mA/cm<sup>2</sup>) of catalysis at pH 10.5, outperforming
all the other literature systems. These observations may provide a new strategy
for the design of earth-abundant transition metal-based water oxidation
catalysts.
Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media
