Optimum loading concentrations of polyoxometalates in layer-by-layer films for oxygen reduction in acidic media

POLY 87

James R. Mason, euryalusnisus@yahoo.com1, Ritesh N. Vyas, riteshnvyas@gmail.com2, Ku’yen Li2, David L. Cocke, cockedl@hal.lamar.edu3, and Bin Wang, bin.wang@lamar.edu2. (1) Department of Chemistry, Lamar University, 4400 MLK blvd, P.O. Box 10053, beaumont, TX 77710, (2) Department of Chemical Engineering, Lamar University, 4400 MLK blvd, P.O. Box 10053, Beaumont, TX 77710, (3) Departments of Chemistry and Chemical Engineering, Lamar University, P.O. Box 10022, Beaumont, TX 77710
Multilayer films with anionic phosphotungstic acid (PW12) clusters and cationic poly(diallyl dimethyl ammonium chloride) (PDDA) polyelectrolyte have been fabricated using electrostatic layer-by-layer self-assembly (LbL) method onto electrodes. The ionic strength and the concentrations of the dipping solutions were varied to obtain films with optimum loading concentrations of these polyoxometalate clusters on the electrode. The calculated surface coverage of PW12 and the corresponding electrochemical catalytic activity for oxygen reduction in acidic media were compared for each film. The increase in the surface coverage of PW12 at increasing ionic strengths of dipping solutions proved to increase the diffusivity of oxygen inside the multilayer assembly. An optimum catalytic activity was found in (PW12 ⃒PDDA)10 films with a PW12 surface coverage of 3.95 × 10-10 mole/cm2. However, with more layers, the catalytic activity of the LbL structures was reduced because of the higher oxygen-diffusion-resistance.
 

Undergraduate Research in Polymer Science
1:30 PM-4:50 PM, Sunday, April 6, 2008 Hilton New Orleans Riverside -- Grand Salon 16, Oral

Division of Polymer Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008