Metal nanoparticles with unusual catalytic and electronic properties have become an essential part of fuel and gas processing.[1-2] To use the full potential of the heterogeneous catalysts, metal nanoparticles free of any surfactants or reactants must be immobilized homogeneously on a specific supporting material. Since the support should be both chemically and physically stable, porous materials (preferably with a large surface area) such as titanium oxide, silica and carbon black have been used.
Laser ablation is a well established method for the generation of surfactant and reactant-free metal nanoparticles. It involves the utilization of laser energy focused on a bulk target immersed in a solvent. The vaporized material then condenses as nanoparticles, forming a colloidal suspension that is ready to be supported. For more details please review our blog on “Laser Ablation — An Effective Preparative Method for Nanoparticles” or the most recent and comprehensive review article listed in our references below.[6] Real-time video is also available on YouTube.
Fig. 1. “Ligand-coated” and “ligand-free”nanoparticles preparedby
wet-chemical and laser ablation methodologies
Nanoparticles prepared by wet chemical methodology are usually coated by surfactants or ligands. The efficiency of particle deposition on supports is very sensitive to ligand concentration. Moreover, for effective catalytic performance it is critical to remove those hydrocarbons from the particles prior to use. The ligand removal is a very challenging process and can be accompanied by unwanted side effects such as metal particle agglomeration, corrosion, ripening, etc. Ligand-free nanoparticles generated by laser ablation show two orders of magnitude higher adsorption efficiency under ambient conditions without pre or post-treatment of the adducts and products.
Fig. 2. 10 wt% gold nanoparticles on TiO2 as supporting material
We offer a variety of surfactant free gold and platinum nanoparticles on different supports in collaboration with Particular GmbH (examples below).
Product # |
Nanoparticle metal |
Metal Loading |
Support Material |
Platinum |
1 % |
Titania (anatase/rutile) |
|
Platinum |
1 % |
Titania (anatase) |
|
Platinum |
1 % |
carbon black |
|
Platinum |
5 % |
carbon black |
|
Platinum |
10 % |
Titania (anatase/rutile) |
|
Platinum |
10 % |
Titania (anatase) |
|
Platinum |
10 % |
carbon black |
|
Platinum |
20 % |
carbon black |
|
Platinum |
30 % |
carbon black |
|
Gold |
1 % |
Titania (anatase/rutile) |
|
Gold |
1 % |
Titania (anatase) |
|
Gold |
1 % |
carbon black |
|
Gold |
5 % |
carbon black) |
|
Gold |
10 % |
Titania (anatase/rutile) |
|
Gold |
10 % |
Titania (anatase) |
The absence of ligands not only improves the affinity to carrier surfaces, but also prevents any catalytic centers from being blocked significantly increasing the catalytic activity. For this reason laser-generated nanoparticles immobilized on particulate supports are an efficient and effective tool in heterogeneous catalysis.
References:
For more details on these products please see our Literature Sheet:
Supported Nanoparticles from Laser Ablation in Liquids
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