Preparation Of Pt - Based Nanocatalyst By Layer Self - Assembly Method And Its Electrocatalytic Performance

Recently, direct methanol fuel cells (DMFCs), as an alternative clean energy source, have been attracted extensive attention due to their high efficiency, system simplicity, and environmental friendliness, and thus been applied in electric vehicles successfully. Pt-based electrocatalysts are regarded as the most popular and effective anodic electrocatalysts for DMFCs. However, the large-scale commercialization of DMFCs is still hindered by some technological challenges, including the less catalytic activity, poor durability, the high cost of the Pt-based electrocatalysts. As such, tremendous efforts have been devoted to improving the catalytic efficiency and meanwhile reducing the compusion of Pt. Therfore, it is of great importance to improve the electrocatalytic performances of the Pt-based anodic catalysts. In this thesis, we innovatively developed the following three methods to improve the electrocatalytic performances of the Pt-based electrocatalysts for DMFCs.1. Synthesis of Pt hollow nanotubes and their electrocatalytic performance for methanol oxidationIt is well-established that nanostructure engineering could not only effectively enhace the atom utilization efficiency, but also could improve the electrocatalysis performance of a noble metal-based nanocatalyst. In this work, we synthesized hollow nanotubes to improve the activity and stability of the catalyst. The Pt hollow nanotubes (Pt-NTs) were rationally synthesized by a layer-by-layer self-assembly method using FeOOH as a sacrificial template. Compared with the commercial Pt-black catalyst, the as-synthesized Pt-NTs exhibited better catalytic performance and stability to the oxidation of methanol, owing to their particular hollow nanotube structure and high atom utilization efficiency.2. Carbon nanotubes supported cerium dioxide and platinum nanohybrids: Layer-by-layer synthesis and enhanced electrocatalytic activity for methanol oxidationWe successfully synthesized carbon nanotubes (CNTs) supported cerium dioxide and platinum (Pt/CeO2/CNTs) nanohybrids via layer-by-layer assembly. By comparison of the electrocatalytic properties of the Pt/CeO2/CNTs with the Pt/CNTs, we systematically investigated the promotion effect of CeO2 on the Pt/CeO2/CNTs catalysts towards methanol oxidation. It was found that the introduction of CeO2 not only enhanced the electrocatalytic activity and stability of the Pt/CeO2/CNTs catalyst for methanol oxidation but also minimized the CO poisoning, probably accounting for the good oxygen carrying capacity of CeO2 and its high stability in acidic solution.3. General self-assembly route toward sparsely studded Noble-metal nanocrystals inside graphene hollow sphere network for ultrastable electrocatalyst utilizationIn this work, we rationally designed and constructed a novel type of sparsely studded Noble-metal nanocrystals inside grapheme hollow sphere network (abbreviated as Noble-metal@G HSN) through an electrostatic-attraction-directed self-assembly approach. The formation of Pt@G and Pd@G hollow sphere networks had been illustrated as examples using SiO2 spheres as templates. Moreover, the electrocatalytic performance of the Pt@G HSN for methanol oxidation reaction had been examined as a proof-of-concept demonstration of the compositional and structural superiorities of Noble-metal@G HSN toward electrocatalyst utilization. The as-prepared Pt@G HSN manifested higher catalyticactivity and markedly enhanced long-term durability in comparison with commercial Pt/C catalyst.