@phdthesis{oai:kyutech.repo.nii.ac.jp:00005982,
 author = {Wang,  Nannan},
 month = {2019-06-11},
 note = {1 Background||2 Experimental section for electrode preparation, physic characteristic, and data analysis||3 PtM (M: Fe, Co, Ni) alloys as the ORR electrocatalysts with the facile operating conditions||4 Temperature-dependence of electrocatalytic activity for dual transition metals embedded in P-doped porous carbon used as ORR catalyst||5 2-D material MXene Nb2C synthesized by the molten salt method at the low temperature as the catalytic support to enhance the oxygen reduction reaction, Polymer electrolyte membrane fuel cell (PEMFC) is recognized as one of the most effective, environmental-friendly, and futuristic technologies for clean energy. However, the low conversion efficiency of the oxygen reduction reaction (ORR) catalysts hindered its further practical application. Because a commercial and efficient ORR catalyst, Pt nanoparticles loaded on the carbon (XC-72) cannot meet the demand for widespread application due to its excessive cost, poor durability, and fast poisoning during the reaction. Identifying plausible solutions to these problems is still a challenge. In this thesis, we focused on the development of the novel efficient catalysts for ORR with ultra-low Pt loading amount and Pt-free materials. In order to further improve catalytic activity, we also synthesized a new 2-D material Nb2C to replace the carbon support of the catalyst. In chapter 1, the fundamental theory and the structure of fuel cells were briefly described. The theoretical analyses of the ORR process were also introduced. Furthermore, the recent development of the ORR catalysts was summarized. Finally, we exhibited the issues of ORR catalysts and the purposes in this thesis. In chapter 2, the reagents and instruments used in this work were summarized. We also introduced the preparation methods of the working electrode and the characterizations. Finally, the electrochemical measurements and analyses, such as the cyclic voltammetry (CV) and the linear sweep voltammetry (LSV) were presented. In chapter 3, the synthesis procedure for PtM (M: Fe, Co, Ni) alloy samples through a simple method under the mild conditions was described. In detail, the transition metals were doped into the Pt nanoplate crystals to form PtM (M: Fe, Co, Ni) alloys. The physical characterizations proved that the PtFe alloy has a well-defined, homogeneous, and ultra-small particle size morphology. We found that the morphology contributes the higher catalytic activity. Finally, the PtM (M: Fe, Co, Ni) alloys are used as the ORR catalyst, and they show the excellent catalytic activity and stability both in the acidic and alkaline medium. In chapter 4, 3 kinds of Pt-free catalysts were successfully designed and synthesized. A metal-organic framework (MOF) was used as a precursor. The influences of the carbonization temperature and the ratios of the two transition metals were studied in terms of the ORR performance. Meanwhile, the synergistic effect of the dual transition metals was considered to have a positive impact on improving the electrocatalytic activity. The electrochemistry analyses displayed that FCPA-900 shows the best ORR catalytic activities, because of the larger specific surface area and the better-defined amorphous carbon structure. In chapter 5, firstly, in order to obtain a 2-D MAX Nb2AlC under a mild condition, we studied on the influence of target materials under the different conditions, such as reaction method, type of molten salts flux, reaction temperature, and reaction time. The synthesis temperature of the MAX Nb2AlC was successfully decreased from 1600oC to 1000oC by using the molten salt assisted solid-state reaction. The reaction mechanism of the Nb2AlC was also investigated, and the effect of the NaCl flux on Nb2AlC synthesis was confirmed. Secondly, the multilayer 2-D MXene Nb2C material was obtained by etching the MAX Nb2AlC. Finally, the ORR catalytic activity of the Pt nanoparticles loaded on the multilayer 2-D MXene Nb2C was studied. The results of the electrochemical measurements show that the 2-D MXene Nb2C is an excellent support material to replace carbon for the Pt loading catalyst. In chapter 6, the general conclusions and prospects were presented. The electrochemical performance of the obtained Pt-based and Pt-free catalysts for the ORR was summarized. Further studies need to focus on improving the stability, promoting the efficiency, and developing new high-performance ORR catalysts., 九州工業大学博士学位論文 学位記番号：生工博甲第325号 学位授与年月日：平成30年9月21日, 平成30年度},
 school = {九州工業大学},
 title = {Development of Ultra Low Pt Electrochemical Catalysts of Oxygen Reduction Reaction for Fuel Cells},
 year = {}
}