Polar Substrates and Nonstoichiometric Surfaces: New Routes to Active and Controllable Heterogeneous Catalysts

2013 Spring Symposium

Andrew M. Rappe
Pen­ner­gy Co-Direc­tor
Depart­ment of Chem­istry
Uni­ver­si­ty of Penn­syl­va­nia
Philadel­phia, PA 19104

Abstract — The quest to design sur­faces with use­ful cat­alyt­ic activ­i­ty has received a dra­mat­ic boost from mod­ern tech­niques of oxide epi­tax­i­al growth and char­ac­ter­i­za­tion. This unprece­dent­ed exper­i­men­tal con­trol of oxide sur­faces opens great oppor­tu­ni­ties to design new cat­a­lysts using the­o­ry and mod­el­ing. In this talk, I will describe a vari­ety of new approach­es for tai­lor­ing sur­face prop­er­ties by con­trol­ling oxide com­po­si­tion and struc­ture, before focus­ing on two spe­cif­ic exam­ples. 1. Polar oxides show struc­tur­al defor­ma­tions that change the struc­ture and com­po­si­tion of sur­faces. 2. Anneal­ing com­plex oxides can lead to sur­face recon­struc­tions with com­po­si­tions dif­fer­ent from any bulk mate­r­i­al. These tech­niques lead to sur­faces with under­co­or­di­nat­ed tran­si­tion met­al cations that should offer nov­el reac­tiv­i­ty.

Andrew M. Rappe

Andrew M. Rappe

Biog­ra­phy — Andrew M. Rappe is a Pro­fes­sor of Chem­istry and Pro­fes­sor of Mate­ri­als Sci­ence and Engi­neer­ing at the Uni­ver­si­ty of Penn­syl­va­nia. He received his A. B. in “Chem­istry and Physics” sum­ma cum laude from Har­vard Uni­ver­si­ty in 1986, and his Ph. D. in “Physics and Chem­istry” from MIT in 1992. He was an IBM Post­doc­tor­al Fel­low at UC Berke­ley before start­ing at Penn in 1994.

Andrew received an NSF CAREER award in 1997, an Alfred P. Sloan Research Fel­low­ship in 1998, and a Camille Drey­fus Teacher-Schol­ar Award in 1999. He was named a Fel­low of the Amer­i­can Phys­i­cal Soci­ety in 2006.

Andrew is one of the two found­ing co-direc­tors of Pen­ner­gy: the Penn Cen­ter for Ener­gy Inno­va­tion. He is also one of the found­ing co-direc­tors of the VIPER hon­ors pro­gram at Penn, the Vage­los Inte­grat­ed Pro­gram in Ener­gy Research.

His cur­rent research inter­ests revolve around fer­ro­elec­tric phase tran­si­tions in oxides, sur­face chem­istry and catal­y­sis of com­plex oxides, and the inter­play between the two: a) He helped estab­lish rela­tion­ships between com­po­si­tion and fer­ro­elec­tric phase tran­si­tion tem­per­a­ture in bis­muth-con­tain­ing per­ovskites oxides, b) He pre­dict­ed that chang­ing chem­i­cal vapor com­po­si­tion above a fer­ro­elec­tric oxide could reori­ent its polar­iza­tion, c) He revealed the mech­a­nism of domain wall motion in fer­ro­elec­tric oxides, d) He showed that chang­ing fer­ro­elec­tric polar­iza­tion dra­mat­i­cal­ly changes cat­alyt­ic activ­i­ty of sup­port­ed met­al films and nanopar­ti­cles, and e) He uses com­pu­ta­tion­al mate­ri­als design to invent new fer­ro­elec­tric pho­to­voltaics for solar appli­ca­tions.