Nanoparticle Layer-by-Layer Assembly for Fuel Cell Electrodes Anastasios P. Angelopoulos, Department of Chemical and Materials Engineering, University of Cincinnati Step 1. Nanoparticle Synthesis A synthesis technique has been developed that yields stable, mono-disperse molecular clusters of platinum monomers in colloidal suspension with high electrocatalytically active surface area based on the adsorption and desorption of protons in acidic media yet free from site specific interactions with a support structure. Specifically, we reduce a platinum precursor with a stannous salt through the formation of an oxidant-reductant complex and subsequent removal of the reducing agent according to: where x = stannous ions not oxidized by platinum, ejected from the complex, and remain attached to particle surface. RESULTS. HAADF-STEM micrographs of platinum nanoparticles synthesized from a reducing Sn(II)/Pt(IV) ratio in solution as indicated in the table below. Particle size and crystallinity increases progressively as the Sn(II)/Pt(IV) ratio falls from 9 to 1.5. (inset) The Fourier transforms of the Pt crystalline particles. Next Steps.Improve electrolyte purity for electrochemical characterization, LBL assembly SAXS characterization, refine tin removal process, durability assessment.