| AVS 60th International Symposium and Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | A.S. Ahsen, Gebze Institute of Technology, Turkey |
| Authors: | A.S. Ahsen, Gebze Institute of Technology, Turkey O.K. Ozdemir, Yildiz Technical University, Turkey O. Ozturk, Gebze Institute of Technology, Turkey H. Yan, University of South Carolina R.P. Galhenage, University of South Carolina D.A. Chen, University of South Carolina |
| Correspondent: | Click to Email |
Pt and Pt-Co bimetallic alloy clusters were grown both on commercial hydrophobic carbon paper substrate and on TiO2(110) crystal. Pt and Pt-Co bimetallic surfaces were deposited on carbon paper substrate using dc magnetron sputtering to investigate electrocatalytic properties of Pt-Co interaction toward the oxygen reduction reaction in 0.5M H2SO4 solution by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) on rotating disc electrode (RDE). Pt‐Co alloy catalysts showed significant improvement on catalytic activity against the pure platinum catalysts. The increase of Co content leads to rise in the electrochemical active surface area (EASA) and improved Pt utilization. The improvement is closely related with the electronic interaction of Pt with Co and modification of the surface electronic structure using bimetallic alloy clusters. Pt-Co alloy surface as a catalyst improved also polymer electrode membrane fuel cell (PEM) performance and deceased Pt usage compared to pure Pt catalyst. Bimetallic clusters are investigated on TiO2 crystal surface to clarify the Pt-Co interaction.
The growth, nucleation and chemical activity of bimetallic Pt-Co clusters on TiO2(110) crystal have been investigated by using scanning tunneling microscopy (STM) and low energy ion scattering (LEIS). STM results demonstrate that the mobility of Pt atoms on TiO2(110) crystal is higher than mobility of Co atoms. For equivalent coverage of Pt and Co the number of cluster density of Pt is higher than for Co. For clusters with a total coverage of 0.25 ML, the cluster density increases as the fraction of Co increases. Next, the surface compositions of Pt on Co and Co on Pt bimetallic clusters are studied using low energy ion scattering (LEIS). The bulk composition is ranging from 100% Pt to 75%, 50%, 25% Pt and 100% Co within total metal coverage of 0.25 ML. For all coverages the cluster surfaces are covered by Pt, which is relatively mobile compared to Co. This explains also the electrochemical improvement. After annealing to 900K all clusters become encapsulated by titania but for the bimetallic clusters the interaction of Co with Pt can be observed up to 600K.