SYNTHESIS, CHARACTERIZATION AND PERFORMANCE TESTING OF PT- BASED ELECTROCATALYSTS FOR LOW TEMPERATURE PEM FUEL CELLS
Open Access
- Author:
- Gong, Yanming
- Graduate Program:
- Energy and Geo-Environmental Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 24, 1971
- Committee Members:
- Yaw D Yeboah, Committee Chair/Co-Chair
Serguei Lvov, Committee Member
Andre Louis Boehman, Committee Member
Thomas E Mallouk, Committee Member - Keywords:
- electrocatalyst
cathode
PtCr
PtFe
Methanol
PEM fuel cell - Abstract:
- The oxygen reduction reaction (ORR) activity on the cathode plays a significant role in deciding the overall performance of proton exchange membrane (PEM) fuel cells. Dramatic effort has been devoted to the attempt to enhance the catalytic activity and reduce the overpotential caused by the irreversible oxygen reduction reaction on the cathode side of PEM fuel cell. To reduce the electrode overpotential and increase cell performance, the exploration of new catalytic materials as substitutes for the traditionally preferred platinum-only catalyst has been extensively carried out in recent decades. Appling transition metal modified Pt bimetal electrocatalyst instead of Pt is one of the main approaches for this purpose. The objectives of this research are to identify potential Pt-modified electrocatalysts for the cathode in hydrogen and methanol PEM fuel cells and provide better understanding of the promoting effect of the synthesized electrocatalysts as a function of material atomic ratio, particle distribution and alloying composition. The physical properties and ORR activity of carbon supported PtFe and PtCr electrocatalysts were studied extensively. All the electrocatalysts were prepared by colloidal method and subsequent catalytic properties and performance were studied. Catalyst surface area was determined by BET nitrogen adsorption and electrochemical methods. Particle size and their distribution were studied by transmission electron microscopy (TEM). X-ray diffraction characterization (XRD) measurements were conducted to determine the crystallite structure. Electrocatalyst activity was evaluated by rotating disc electrode (RDE) and single cell measurements. It can be concluded from the experiment results that PtFe/C and PtCr/C electrocalysts could be better replacements for conventional Pt/C as the cathode of PEM fuel cell. The Pt9Fe1/C and Pt4Cr1/C gave the best catalytic activity which was demonstrated both on RDE and single cell measurements. For H2 PEM fuel cell testing, both of Pt9Fe1/C and Pt4Cr1/C showed comparable ORR results with Pt/C; for methanol PEM fuel cell, they displayed a dramatically enhanced oxygen reduction capability and methanol tolerance, compared to Pt/C. In addition, it was found that the catalytic activity of the studied PtFe and PtCr electrocatalysts varied dramatically at various chemical compositions; also, alloy structure may not be the predominant factor in deciding the enhanced electrocatalytic activity of bimetal electrocatalysts.