09:00 AM - 10:00 AM
Huiyuan Zhu, Dept of Chemistry, Brown University, Providence, Rhode Island
Liane Russell Candidate Seminar
Building 4500-N, Weinberg Auditorium
Email: Tim McKnightPhone:
Controlled synthesis of nanoparticles (NPs) is a key to developing highly efficient and stable catalysts for various reactions, including those involved in energy conversion systems, such as the proton exchange membrane fuel cell, and those used for catalytic bio-detections. The organic-solution based chemical synthesis provides a robust approach to obtaining well-defined NPs with monodisperse morphologies and assuring precise control over NP physicochemical parameters (size, shape, composition and crystal structure). It thus allows for a better understanding of the parameter-property correlation and the optimization rules of advanced NP catalysts. In my presentation, I will concentrate on the following three NP catalysts:  Monodisperse FePt NPs are synthetically controlled from chemically disordered face centered cubic (fcc) structure to ordered face centered tetragonal (fct) structure. The NP’s electrocatalytic efficiency in oxygen reduction reaction (ORR) can be drastically increased by the fcc-fct structural transition. The relevant theoretical calculations of the structure-induced catalytic enhancement will also be discussed to provide a predictable model for future design and optimization of ORR nanocatalysts.  One-dimensional FePt, CoPt and FePtM (M = Cu, Ni) nanowires (NWs) are synthesized and converted to FePtM/Pt core/shell structure. These FePtM/Pt NWs show superior performance in catalyzing oxygen reduction reaction (ORR) in acidic solution. Furthermore, seed-mediated approach is applied to produce FePtNi/Pt core/shell NWs. Tailoring the NW thickness and the surface structure (Pt-skeleton and Pt-skin) leads to an optimized catalytic performance towards ORR.  Examples of some other NPs will also be included, such as the nanoparticles of MnAu used for the electrochemical detection of H2O2 and sub-10 nm M (II)-substituted magnetite MxFe3-xO4 (M=Fe, Cu, Co, Mn) NPs as the alternatives for Pt to catalyze ORR in alkaline solution and structure-controlled NPs FePtAu for formic acid oxidation reaction (FAOR) as well.