NORTHWESTERN UNIVERSITY Atomically-Precise Synthesis of Platinum catalysts on Strontium Titanate using Atomic Layer Deposition A DISSERTATION SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS For the degree DOCTOR OF PHILOSOPHY Field of Materials Science and Engineering By

................................................................................................................... 3 Acknowledgements....................................................................................................... 5 List of Figures........................................................................................................... 10 List of Tables.......................................................................................................... 16 Chapter I: Metal Oxide Supported Noble Metal Catalysts................................................. 17 1.1: Introduction............................................................................................................. 18 1.2: Heterogeneous catalyst preparation.......................................................................... 21 1.2.1 Traditional methods for preparation of catalytic material............................... 21 1.2.2 New application of atomic layer deposition for catalyst synthesis.................. 23 Chapter II: Synthesis Approach of High Surface Area Catalytic Support with Specific Exposed Surfaces......................................................................................................................... 29 2.1: Introduction.............................................................................................................. 30 2.2: STO-NCs synthesis from lamella micro-emulsion.................................................... 32 2.2.1 STO nanomaterials synthesis from different microemulsion structures......... 32 2.2.2 Electron microscopy....................................................................................... 33 2.3: Result and discussion............................................................................................... 34 2.3.1 Morphology of as-synthesized STO-NCs...................................................... 34 2.3.2 Mechanism of formation of STO-NCs beyond synthesis............................... 36 2.3.3 Influence of covered surfactant to surface properties..................................... 39 2.3.4 Surfactant removal or replacement................................................................. 40 Chapter III: ALD Synthesis of Platinum Nanoparticles on Single-crystal SrTiO3............. 50 3.1: Introduction.............................................................................................................. 51 3.2: Experimental............................................................................................................ 53 3.2.1 Sample preparation and wet chemical etching................................................ 53 3.2.2 X-ray photoelectron spectroscopy (XPS)........................................................ 55 3.2.3 Transmission electron microscopy sample preparation and image recording. 56 3.2.4 Platinum ALD.................................................................................................. 57 3.3: Result and discussion............................................................................................... 58 8 3.3.1 Carbon removal and hydroxyl group enrichment on SC-STO (100) surface.58 3.3.2 Morphology and composition study of SC-STO before ALD........................ 60 3.3.3 Study of deposited Pt nanoparticles on SC-STO substrates with different treatment................................................................................................................... 60 3.4: Conclusion................................................................................................................ 61 Chapter IV: Controllable ALD Synthesis of Platinum Nanoparticles by Tuning Different Synthesis Parameters.................................................................................................................. 72 4.1: Introduction............................................................................................................. 73 4.2: Experimental............................................................................................................. 76 4.2.1 Morphology and surface structure of two types of STO-NCs......................... 76 4.2.2 Platinum ALD deposition................................................................................ 77 4.2.3 Characterization............................................................................................... 79 4.3: Results and discussion.............................................................................................. 80 4.3.1 General morphology and structure of Pt/STO-NCs........................................ 80 4.3.2 Size measurement from HAADF images depends on probe size.................... 81 4.3.3 Temperature dependence of Pt ALD synthesis............................................... 83 4.3.4 Dependence of size and density of Pt nanoparticles on number of cycle and ALD method............................................................................................................. 85 4.3.5 Influence of supporting material on the structure and loading of ALD formed Pt nanoparticle......................................................................................................... 87 4.3.6 Role of reagent in ALD process..................................................................... 89 4.3.7 Pt nanoparticle formation through nucleation and diffusion controlled growth process...................................................................................................................... 92 4.4: Conclusion................................................................................................................. 100 Chapter V: Winterbottom Shape Tailoring of Platinum Nanoparticles on Perovskite Oxides BaxSryTiO3................................................................................................................................. 123 5.