Research shows that the intercalation of metal ions (i.e., Cu2+ and Ni2+) into the interlayer region of the layered manganese oxide, birnessite, results in an active electrocatalyst for the oxygen evolution reaction (OER) in both a neutral and alkaline medium. Unmodified birnessite displays a relatively high overpotential for water oxidation (700 mV at 10 mA/cm2) and large Tafel slope of 240 mV/decade. It is shown that through metal intercalation the overpotential can be significantly lowered. Copper intercalation results in a lowering of the overpotential to 600 mV, while the intercalation of Ni2+ lowers the overpotential to 400 mV (lower than pure Ni hydroxide). In the Ni2+/birnessite circumstance the Tafel slope decreases to 65 mv/decade. In the Cu2+/birnessite case, density functional theory calculations show that the intercalation of copper into a layered MnO2 model structure leads to a change of the electronic properties of the material from a semiconductor to a more metallic like structure. Molecular Dynamic Simulation studies suggest that the intercalation of Ni2+ in to the water-containing interlayer region of birnessite results in enhanced electron transfer rates leading to an improvement in OER catalysis.

Intercalation of metal ions into the interlayer region of layered manganese oxide for improved water oxidation electrocatalysis

253rd National Meeting (2017)

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