Experimental and Theoretical Studies of Novel Electrocatalysts

2010 Spring Symposium

 
Jing­guang G. Chen
Cen­ter for Cat­alyt­ic Sci­ence and Tech­nol­o­gy
Depart­ment of Chem­i­cal Engi­neer­ing
Uni­ver­si­ty of Delaware
Newark, DE 19716


Abstract — Met­al car­bides [1–3] and bimetal­lic alloys [4–7] often show nov­el cat­alyt­ic and elec­tro­cat­alyt­ic prop­er­ties. How­ev­er, it is dif­fi­cult to know a pri­ori how the chem­i­cal prop­er­ties of par­tic­u­lar car­bide and bimetal­lic sys­tems will be mod­i­fied rel­a­tive to the par­ent met­als. In the past few years our research group has inves­ti­gat­ed the nov­el cat­alyt­ic prop­er­ties of var­i­ous car­bide and bimetal­lic sys­tems, using a com­bi­na­tion of Den­si­ty Func­tion­al The­o­ry (DFT) cal­cu­la­tions, sur­face sci­ence stud­ies on sin­gle crys­tal sur­faces, and reac­tor and fuel cell stud­ies of sup­port­ed cat­a­lysts. The gen­er­al trends from the exper­i­men­tal and the­o­ret­i­cal stud­ies of car­bide [1] and bimetal­lic sur­faces [4] have been sum­ma­rized in recent reviews.

In this talk we will describe the uti­liza­tion of tung­sten car­bides as poten­tial anode elec­tro­cat­a­lysts for Direct Methanol Fuel Cells (DMFC). Cur­rent­ly, the anode elec­tro­cat­a­lysts for DMFC are Pt and Pt/Ru, which are dis­ad­van­ta­geous in terms of the pro­hib­i­tive­ly high costs and their sus­cep­ti­bil­i­ty to be poi­soned by CO. We will describe how to con­trol the decom­po­si­tion path­ways of methanol on sin­gle crys­tal sur­faces of tung­sten car­bides under well-con­trolled ultra­high vac­u­um (UHV) con­di­tions. We will also dis­cuss the syn­the­sis of phase pure tung­sten car­bide elec­trodes using Phys­i­cal Vapor Depo­si­tion (PVD) to bridge the “mate­ri­als gap” between sin­gle crys­tal sur­faces and poly­crys­talline films. We will then present our results of the elec­tro­chem­i­cal eval­u­a­tion of the tung­sten car­bide elec­trodes to bridge the “pres­sure gap” between UHV envi­ron­ment and elec­tro­chem­i­cal con­di­tions. We will also briefly dis­cuss the ther­mo­dy­nam­ic sta­bil­i­ty and kinet­ic mea­sure­ments regard­ing the bimetal­lic sur­faces in the pres­ence of oxy­gen under both UHV [8] and atmos­pher­ic [9] con­di­tions, which should help iden­ti­fy active and sta­ble bimetal­lic cath­ode elec­tro­cat­a­lysts in the Oxy­gen Reduc­tion Reac­tion (ORR) in fuel cells.

[1] Hwu & Chen, Chem­i­cal Reviews, 105 (2005) 185–212.
[2] Na, Zhang, Zheng, Wang & Chen, Angew. Chem. Int. Ed. 47 (2008) 8510.
[3] Weigert, Stot­tle­my­er, Zell­ner & Chen, J. Phys. Chem. C, 111 (2007) 14617.
[4] Chen, Men­ning & Zell­ner, Sur­face Sci­ence Reports, 63 (2008) 201–254.
[5] Hwu, Eng & Chen, J. Am. Chem. Soc. 124 (2002) 702.
[6] Kitchin, Norskov, Barteau & Chen, Phys. Rev. Lett. 93 (2004) 156801.
[7] Muril­lo, Goda & Chen, J. Am. Chem. Soc. 129 (2007) 7101.
[8] Men­ning & Chen, J. Chem. Phys. 130 (2009) 174709.
[9] Men­ning & Chen, J. Pow­er Sources, 195 (2010) 3140.

Speaker’s Biog­ra­phy — Jing­guang Chen is the Claire D. LeClaire Pro­fes­sor of chem­i­cal engi­neer­ing. He also holds the posi­tions of the Inter­im Direc­tor of the Uni­ver­si­ty of Delaware Ener­gy Insti­tute and Co-Direc­tor of the Ener­gy Fron­tier Research Cen­ter at the Uni­ver­si­ty of Delaware. He received his Ph.D. degree from the Uni­ver­si­ty of Pitts­burgh 1988. He spent one year in Ger­many as a Hum­boldt Post­doc­tor­al Fel­low before start­ing his career at the Exxon Cor­po­rate Research Lab­o­ra­to­ries. In 1998 he accept­ed a fac­ul­ty posi­tion at the Uni­ver­si­ty of Delaware and served as the Direc­tor of the Cen­ter for Cat­alyt­ic Sci­ence and Tech­nol­o­gy (CCST) from 2000–2007. He has 200 jour­nal pub­li­ca­tions and 17 US patents. He is very active in serv­ing the sur­face sci­ence and catal­y­sis com­mu­ni­ties, includ­ing respon­si­bil­i­ties as the Chair for the Gor­don Research Con­fer­ence on Catal­y­sis in 2002, the Chair of the Philadel­phia Catal­y­sis Club in 2004, the Catal­y­sis Sec­re­tari­at of the Amer­i­can Chem­i­cal Soci­ety in 2007, and the Board of Direc­tors for the North Amer­i­can Catal­y­sis Soci­ety. He is also the co-founder and team leader of the first Syn­chro­tron Catal­y­sis Con­sor­tium in the US for the Depart­ment of Ener­gy.