A Novel and Robust Method to Yield Stable, Highly Active and Mass-Produceable Pt3Ni Catalyats
Engineering crystal structures in nanoscale is challenging, yet provides an effective way to improve catalytic performances. Pt-based nanoframes are a new class of nanomaterials that have great potential as high performance catalysts. To date, these nanoframes are formed through acid etching in aqueous solutions, which demands long reaction time and often yields ill-defined surface structures. The present technology provides a method for facile development of high-performance nanoframe catalysts using size and crystallographic face-controlled PtNi4 tetrahexahedral (THH) nanocrystals (NCs) prepared through a colloidal synthesis as precursors. This protocol employs a modification of the Mond process to preferentially de-alloy nickel component in the <100> direction through carbon monoxide (CO) etching of carbon supported PtNi4 THH NCs at an elevated temperature. The resultant Pt3Ni THH nanoframes possess an open, stable and high-indexed microstructure, containing a segregated Pt thin layer strained to the Pt-Ni alloy surfaces, and featuring a down-shift d-band center as revealed by density functional theory (DFT) calculations. These nanoframes exhibit much improved catalytic performance, such as high stability under prolonged electrochemical potential cycles, promoting direct electro-oxidation of formic acid to CO2 and enhancing oxygen reduction reaction activities. Because CO can be generated from the carbon support through thermal annealing in limited amount of air, a common process for pretreating supported catalysts, the technology can be easily adopted for preparing industrial scale catalysts that are made of Pt-Ni and other alloy nanoframes.
- Nanoframes using gas phase reactions that feature fast, stable and large-scale production.
- Resultant nanoframes have better defined surface structure for improving catalytic activity and stability.
- Formation of nanoframes takes only 45 minutes, as opposed to 12 or 24 hours in acid etching approach.
- Developed process can be adopted for other systems, such as Pt-Fe, Au-Fe, Pd-Ni systems, to engineer catalysts with novel hollow structures.
Binghamton University RB513