Mimicking Catalytic Properties of Precious Metals by Using Common Metal Nanostructured Particles.

摘要

This project explores the design, synthesis and testing of novel core-shell nanoparticles, specifically conceived to closely mimic the catalytic activity of platinum, with the aim of providing an engineered substitute to platinum for industrial catalytic applications. A preliminary assessment (based on Norskov d-band model of catalytic phenomena) was conducted for finding transition metal couples, which arranged in core-shell geometry, would present a surface chemical reactivity close to that of platinum. This assessment used existing literature calculations and databases to identify ruthenium shell on nickel core and palladium shell on cobalt core as promising possibilities to mimic platinum reactivity. The research focused on the ruthenium-nickel system, including theoretical calculations using density functional theory, synthesis of Ru-Ni core-shell nanoparticles, nanoscale structural characterization, and comparison of catalytic activity to platinum in a test reaction (ammonia borane dehydrogenation). In addition, Ni-Ru 'alloy' nanoparticles were synthesized and their reactivity compared to that of the Ru-Ni core-shell nanoparticles and platinum. Both the Ru-Ni core-shell nanoparticles and the Ni-Ru 'alloy' nanoparticles showed catalytic activity much higher than that of individual base metals, and in the latter case, the reactivity was quite close to that of platinum for the test case reaction. The results are encouraging to engineer substitutes to precious metals, however further tests are needed to check reactivity for other reactions of interest and ensure stability of the catalytic nanoparticles under harsher conditions (e.g., higher temperatures and/or more reactive gas environments).