Theory-guided design of nanoscale multi-metallic catalysts for fuel cells
- Texas A & M Univ., College Station, TX (United States). Dept. of Chemical Engineering
- Texas A & M Univ., College Station, TX (United States). Dept. of Chemical Engineering, and Dept. of Electrical and Computer Engineering
This project aims to address the following aspects of the oxygen reduction reaction on multimetallic nanocatalysts: 1. Elucidate physical and chemical aspects of electron and proton transfer 2. Incorporate local and nonlocal field effects to the analysis 3. Investigate the performance of bimetallic and multimetallic nanocatalytic ensembles a. Explore combinations of Pt with other non-precious metals b. Explore theoretically the performance of active catalytic sites/substrate/proton-carrier systems towards maximizing oxygen reduction currents. c. Explore compatibility catalyst/substrate/ionic carrier. 4. Investigate nanocatalyst stability under the reaction conditions, effects of pH and overall composition; surface segregation phenomena in nanoclusters. 5. Carry out theory-guided experiments involving electron transfer as proof of concept. Specific objectives for the previous year: Determine trends for catalytic activity towards the oxygen reduction reaction and stability against dissolution of Pt-based alloy nanocatalysts exposed to acid medium. Reactivity and stability trends are sought as a function of surface composition and atomic distribution in the first 2-3 surface layers. Investigate possible mechanisms for metal dissolution. Developing and testing new computational approaches to characterize the catalytic interface. Significant achievements and results for the previous year: Catalytic activity: Variations in atomic distribution (mixed vs. ordered structures) analyzed in small clusters and extended surfaces of PtxPdy at fixed overall composition revealed polarization effects caused by specific electronic density distributions determining trends in reactivity. We studied other bimetallic and trimetallic systems to characterize the ability of various alloy elements for modifying Pt reactivity. We found an interesting parallelism between metalloenzymes and bimetallic nanocatalysts for the oxygen reduction reaction. Along the same lines, we are studying the catalytic ability of nanoparticles inside of dendrimer pockets. Stability of nanocatalysts against dissolution: We developed a systematic thermodynamic analysis based on density functional theory calculations, which allows us to determine the stability against dissolution of platinum and other elements in mono- or multimetallic ensembles. We are currently analyzing the mechanism by which metal dissolution takes place, and the influence of alloy composition and atomic distribution on the dissolution reactions. Development of new computational methodologies for the catalytic interface: The effect of the bulk on a finite cluster is accounted for through a combined Green function—DFT approach developed by one of the PIs. This procedure was further refined to deal with alloy bulk materials, and applied to PtxCoy systems. Potential impact in science and in technologies of interest to DOE. This research will allow design of catalysts for the oxygen reduction reaction with much better activities and durabilities; simultaneously, advancing the fundamental and applied aspects of catalytic reactions such as the physics, the chemistry, methods, and development of accurate guidelines for rational design.
- Research Organization:
- Texas Engineering Experiment Station, College Station, TX (United States).
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- FG02-05ER15729
- OSTI ID:
- 903105
- Report Number(s):
- DOE/ER/-15729-2
- Country of Publication:
- United States
- Language:
- English
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