부산대학교 도서관

Noble metal nanoparticle-based electrocatalysts have impacted greatly the advance of fuel cell technology and electrolytic hydrogen production as an alternative energy source. The surface energy control of nanoparticles, enabled by facet- and alloy composition-controlled synthesis, determines the selectivity of catalysis, and therefore is under intensive research focus. While noble metal electrocatalysts in general show acceptable level of catalytic performances in terms of activity and durability, the scarcity and high cost of them continue to impede the commercialization success of them. Nanoparticle-based heterogeneous catalysis is intrinsically surface driven phenomenon. Therefore, there have been serious attempts to enhance the intrinsic catalytic activity and the sheer number of active sites per a given volume of a nanoparticle catalyst. The forerunner of these approaches has been the development of nanoframe-based nanocatalysts, where our research group leads the global research thrust. There, however, remain daunting challenges for the nanoframe-based catalysts such as further activity enhancement and endowment of structural robustness to the intrinsically flimsy nanoframe structures, and my doctoral study has been devoted to solve these problems In the early part of this thesis, I will describe the general synthetic approaches to hollow or frame-like nanostructures by utilizing leachable template metals such as Ni and Cu. The understanding of thermodynamics and kinetics of metal precursor decomposition and alloy phase formation was critical. Later on, I will describe the nanoframe-fortification strategies for the development of durable catalysts. Specifically, in Chapter 1, I will explain the brief history of nanocatalyst design concept focusing on facet-controlled nanocrystals, alloy compositions, core-shell structure feature and nanocage and nanoframes by using the concept of nanoparticle metastability. Moreover, I will focus on the unresolved issues of nanoparticle catalysis. The structural deformation during the catalysis induces significant problems on the usage of nanoframe-based catalysts. After that, I will describe the nowadays attempts to accomplish the nanocatalyst durability. For example, the introduction of multimetallic compositions and structural fortifying method at the active sites of nanoframeworks. In Chapter 2-3, I will describe the synthesis of PdPt nanotent by structural reorganization of Pd nanoplateinduced by Pt dopant which suggests the metastability of nanotemplates. In addition, I will also describe the synthesis of Rh-based core-shell nanostructure and frame nanostructure via utilization of metastable Cu template and the application in oxygen evolution reaction. In Chapter 4-5, I will describe the structural fortification concept of nanoframe by using the example of Ir-based multimetallic double layered nanoframes, which could be prepared by controlling the sequential decomposition of multiprecursors. In addition, I will describe the synthesis of structurally fortified Pt-based dendrite@frame structures which show highly active and durable catalysis toward the oxygen reduction reaction.