| AVS 61st International Symposium & Exhibition | |
| In-Situ Spectroscopy and Microscopy Focus Topic | Wednesday Sessions |
| Session IS+AS+MC+SS-WeM |
| Session: | In-Situ X-ray Absorption and Raman Spectroscopy |
| Presenter: | Shibi Zeng, University of Notre Dame |
| Authors: | F. Tao, University of Notre Dame J. Shan, University of Notre Dame S. Zhang, University of Notre Dame L.T. Nguyen, University of Notre Dame A. Frenkel, Yeshiva University J. Greeley, Purdue University S. Zeng, University of Notre Dame |
| Correspondent: | Click to Email |
Besides a sophisticated synthesis of bimetallic nanocatalysts in a colloidal solution, a post-synthesis reaction in a gaseous phase is a complementary method to tailor the surface structure and composition of a bimetallic nanocatalyst to tune its catalytic performance. Here we illustrate the capability of creating a new catalyst surface exhibiting a lower activation barrier through segregation of a bimetallic catalyst in a post-synthesis reaction in a reactive gaseous environment. In-situ surface chemistry of bimetallic nanocatalysts were analyzed with AP-XPS. Coordination environment of Pt and Cu atoms under different reaction conditions was tracked with in-situ EXAFS. The surface restructuring was simulated with DFT calculation from thermodynamic,ci point of view. The composition and geometric structure of the newly formed surface of the bimetallic nanocatalysts strongly depend on the reactant gas used in the post-synthesis reaction. A further sequential reaction in a different gas after the initial post-synthesis reaction in a gas forms a different catalyst surface. A post-synthesis reaction of a Pt-Cu regular nanocube (Pt-Cu RNC) in hydrogen forms a near surface alloy (NSA) which exhibits an activation barrier of 39 kJ/mol for CO oxidation, much lower than pure Pt nanocubes. These studies demonstrate a method of tuning catalytic performances and generate another catalytic phase through a post-synthesis reaction in a gas phase.