Multimetallic materials often exhibit enhanced functional properties compared to their parent metals alone. They have a wide range of applications in areas such as hydrogen storage, catalysis, and electrocatalysis. Examples include a dramatic increase in the oxygen reduction activity of Pt catalysts in the presence of subsurface alloy layers, surface-poisoning resistance in formic acid oxidation catalysts, and improved kinetics in hydrogen storage materials. Further, the topology (e.g., particle size, morphology, porosity) exhibited by nanoparticles and nanoporous metals (NPM) plays an important role in determining functional properties. Despite much recent effort to develop approaches to synthesize multimetallic materials, simultaneous control of both surface morphology and composition remains a challenge, particularly at large scale, and with high surface area powders and nanomaterial substrates.  Atomic Layer Electroless Deposition (ALED) is a scalable approach to surface-modified metal powders in which elements more noble than the surface hydrides of the substrate metal are deposited layer-by-layer in surface-limited fashion. In previous studies, ALED has been limited to Pt and Rh as adlayers grown on Pd powders and Pd/C. For better understanding of this technique, we herein expand the scope of ALED by introducing high surface area nanoporous Pt as potential substrate. High-surface-area NPM were synthesized by chemical reduction of metal salts in soft templates and used as substrates for ALED.  Further, we demonstrate monolayer and sub-monolayer deposition of Cu on Pd substrates to prepare bimetallic catalysts with precisely tuned surface stoichiometry for application as oxidation catalysts.  Finally, by varying the concentration of metal salts during deposition, spectroscopic and microscopic characterization suggest that the surface morphology can be tuned between conformal adlayers and thicker layers with lower fractional coverage. With well controlled deposition by ALED, we aim to explore the applications of these bimetallic nanomaterials as potential catalysts and sensors.

Multifunctional bimetallic nanomaterials prepared by atomic layer electroless deposition

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.