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Compensation Effect Exhibited by Gold Bimetallic Nanoparticles during CO Oxidation
Joe Brindle1, Michael M Nigra1
1Department of Chemical Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
ACS Omega
|September 27, 2021
Summary
Bimetallic gold (Au) nanoparticles alloyed with copper (Cu), cobalt (Co), nickel (Ni), palladium (Pd), and ruthenium (Ru) were synthesized and tested for carbon monoxide (CO) oxidation. Some alloys showed improved catalytic activity compared to pure gold.
Area of Science:
- Materials Science
- Catalysis
- Nanotechnology
Background:
- Gold nanoparticles (Au NPs) are established catalysts for CO oxidation.
- Alloying Au NPs with other metals is an active area of research to tune catalytic properties.
- Understanding the impact of alloying metals and synthesis methods on catalytic performance is crucial.
Purpose of the Study:
- To synthesize and characterize TiO2-supported bimetallic Au nanoparticles alloyed with Cu, Co, Ni, Pd, and Ru.
- To evaluate the catalytic performance of these bimetallic alloys in CO oxidation using two different synthesis methods.
- To investigate the relationship between particle size, alloying, synthesis method, and catalytic activity.
Main Methods:
- Synthesis of bimetallic Au alloys using Strong Electrostatic Adsorption (SEA) and Sterically Demanding Ligand Synthesis (SDLS) methods.
- Characterization of synthesized catalysts.
- Evaluation of catalytic activity for CO oxidation under specific reaction conditions.
- In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for mechanistic insights.
Main Results:
- An enthalpy-entropy compensation effect was observed for the tested materials.
- Both enthalpy and entropy of activation generally decreased with decreasing particle size.
- AuCu, AuNi, and AuPd alloys synthesized via SEA showed enhanced CO oxidation activity compared to monometallic Au.
- AuCo and AuRu alloys synthesized via SEA exhibited decreased activity.
- In situ DRIFTS indicated weaker CO interaction with AuCo and AuRu compared to other alloys.
- SDLS method resulted in lower CO oxidation rates, with potential masking of charge transfer effects by ligand interactions.
Conclusions:
- Bimetallic gold alloys, particularly AuCu, AuNi, and AuPd synthesized via SEA, can enhance CO oxidation catalysis.
- The choice of alloying metal and synthesis method significantly impacts catalytic performance and CO interaction.
- Particle size plays a role in the activation parameters (enthalpy and entropy) of the catalytic reaction.
