Journal
ENERGY & ENVIRONMENTAL SCIENCE
Volume 9, Issue 2, Pages 540-549Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5ee02509e
Keywords
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Funding
- Netherlands Organization for Scientific Research (NWO-The Hague) [680-50-1214]
- US Department of Energy through the Center for Molecularly Engineered Energy Materials (MEEM), an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0001342, DE-SC0014213]
- NIH [1S10RR23057]
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A major challenge in the field of water electrolysis is the scarcity of oxygen-evolving catalysts that are inexpensive, highly corrosion-resistant, suitable for large-scale applications and able to oxidize water at high current densities and low overpotentials. Most unsupported, non-precious metals oxygen-evolution catalysts require at least similar to 350 mV overpotential to oxidize water with a current density of 10 mA cm(-2) in 1 M alkaline solution. Here we report on a robust nanostructured porous NiFe-based oxygen evolution catalyst made by selective alloy corrosion. In 1 M KOH, our material exhibits a catalytic activity towards water oxidation of 500 mA cm(-2) at 360 mV overpotential and is stable for over eleven days. This exceptional performance is attributed to three factors. First, the small size of the ligaments and pores in our mesoporous catalyst (similar to 10 nm) results in a high BET surface area (43 m(2) g(-1)) and therefore a high density of oxygen-evolution catalytic sites per unit mass. Second, the open porosity facilitates effective mass transfer at the catalyst/electrolyte interface. Third and finally, the high bulk electrical conductivity of the mesoporous catalyst allows for effective current flow through the electrocatalyst, making it possible to use thick films with a high density of active sites and similar to 3 x 10(4) cm(2) of catalytic area per cm2 of electrode area. Our mesoporous catalyst is thus attractive for alkaline electrolyzers where water-based solutions are decomposed into hydrogen and oxygen as the only products, driven either conventionally or by photovoltaics.
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