|Name||Ms. Emily Johnson|
|Organization or Institution||University of Florida|
Manganese Dioxide Nanoparticle Synthesis on Gold Nanotubes
Emily P. Johnson, Juliette Experton, Charles R. Martin
Department of Chemistry, University of Florida, Gainesville, FL 32611
Manganese dioxide is a naturally abundant material that is of interest for a wide variety of applications including catalysis, electronics and sensing. In lithium-ion batteries, Mn(IV) can be reduced to Mn(III) by intercalating lithium ions to produce LixMnO2. This intercalation mechanism is favored by the porous structure of MnO2. However, Li diffusion can be slow if the MnO2 is too bulky, reducing the capacity and power delivered by the battery. Therefore, there has been considerable interest in developing an efficient method for the synthesis of MnO2 nanoparticles to decrease the diffusion distances for the transport of lithium ions in batteries.
We have previously developed a bipolar electrodeposition method where a voltage was applied across a gold-nanotube membrane to oxidize Mn2+ and form MnO2 nanoparticles at one end of gold nanotubes. In this method, the membrane was placed between a solution of sodium sulfate and a solution of sodium sulfate and manganese(II) acetate. In an attempt to lower the voltage applied across the membrane, we replaced the solution of sodium sulfate by a solution of iron(III) chloride. Surprisingly, the formation of MnO2 was then spontaneous and occurred without applying a voltage across the membrane. MnO2 nanoparticles were not observed when the membrane did not contain gold nanotubes or when the two solutions of manganese acetate and iron chloride were mixed.
In this poster presentation, we will present the mechanism of the formation of MnO2 nanoparticles with iron chloride. We will also show X-ray photoelectron spectroscopy, microscopy and electrochemical characterizations of these nanoparticles.