Electrochemical promotion of Platinum catalyst for combustion reactions.pdf

1、The subject of this thesis is the study of electrochemical promotion of catalysis(EPOC) also called non-Faradaic electrochemical modification of catalytic activity(NEMCA), In EPOC, the application of small current or pot

2、ential on catalysts causesa significant non-Faradaic increase of catalytic activity. In this work, EPOC overplatinum catalyst supported on yttria stabilized zirconia (YSZ) is investigated underambient pressure and high v

3、acuum (HV) conditions. Under ambient pressureconditions, a Permanent-EPOC behavior is obtained upon current interruption whichis related to an oxygen storage process during polarization. In addition, a custom builtHV set

4、up is used to investigate the electrochemical kinetics and EPOC over Pt/YSZcell. During anodic polarization, three types of oxygen storage locations are identified,i.e. Pt/YSZ interface, Pt/gas interface and Pt bulk. The

5、 saturation of the Pt/YSZinterface leads to the migration of the oxygen promoter over the Pt catalyst inducingthe EPOC effect. The bulk storage takes place with prolonged polarization time. Uponcurrent interruption, the

6、stored oxygen is released onto the Pt surface leading toPermanent-EPOC or Persistent-EPOC which is determined by the stability of surfaceoxygen promoter. In addition, by using an anion emission configuration, thephenomen

7、on of 16O- emission from the Pt surface is observed indicating that thesurface promoter exists in the form of 16O- originating from the YSZ lattice. Theapplication of isotopically labeled 18O2 allows discriminating the F

8、aradaic process(16O from the YSZ) from the non-Faradaic process (18O from the gas phase). It'sfound that the EPOC effect and metal support interaction (MSI) effect are differentfacets ofthe same phenomenon, i.e. the prom

9、oting effect of oxygen species from YSZsupport on the catalytic reaction taking place over the catalyst surface. By applicationof a novel bipolar configuration, the imposed galvanostatic step causes significantenhancemen