成果報告書詳細
管理番号20160000000158
タイトル*平成27年度中間年報 固体高分子形燃料電池利用高度化技術開発事業 普及拡大化基盤技術開発 金属原子直接坦持による触媒高性能化コンセプトの提案
公開日2016/5/28
報告書年度2015 - 2015
委託先名学校法人東京理科大学
プロジェクト番号P15001
部署名新エネルギー部
和文要約
英文要約Abstract 
Design of high performance catalysts for PEFC by direct deposition of metal on carbon support

 With a motivation for promoting a catalytic activity for oxygen reduction reaction (ORR) of carbon supported Pt catalyst based on an interaction between carbon and metal particles, Pt particles were directly deposited on carbon nanotubes (CNTs) via arc plasma deposition (APD) process. Whereas the surface of CNTs are generally recognized to have a low affinity for metal particles, TEM images of the obtained samples indicated that the optimal control of APD conditions enabled the deposition of fine (1~3 nm) and densely-dispersed Pt particles on CNTs coated on acetylcellulose films (amounts of coated CNTs: 0.2 mg/cm2) using airbrush method.
 A temperature-programmed desorption (TPD) apparatus was newly designed and developed.
The apparatus is equipped with a sample manipulator that allows for sample temperature variation and precise positioning of the sample, variable leak valve for gas introduction, and retractable and differentially-pumped quadrupole mass spectrometer (QMS) for desorption/reaction products detection. As a first trial, we have measured TPD spectra of H2 from a Pt-dispersed C sample, which was sprayed on a Cu plate. After H2 dosage of 10-10000 L, TPD spectra of H2 were measured by QMS. While little signal was observed at low dosages, a desorption peak was observed at 300 K at a high dosage. After 10000 L dosage, furthermore, a significant intensity appeared above 400 K. The signal at 300 K is considered to originate from adsorption on the Pt catalysts.
The group of University of Tokyo focuses on the atomic arrangements and electronic structure of Pt/CNT catalysis, which is provided by APD method in the group of Tokyo Science University. The obligation of my group is to understand the electronic structure of the interface via a first principles calculation. In this year, we have performed the calculation with various conditions. Especially, we investigated the effect of van der Waals (VdW) interaction and spin-orbit interaction on the calculation results. By investigating the VdW interaction, it was found that the VdW interaction is essential to reproduce the lattice constant of the layered graphite. In addition, the spin-orbit interaction changes the electronic structure of Pt and Au metals. In the next year, we will investigate the Pt/CNT interaction using the first principles calculation.
Submonolayer dissolution of platinum (Pt) nanoparticles under potential cycling is specified by a channel flow double electrode system. Dissolution of Pt2+ starts at 0.6 V (vs. standard hydrogen electrode) in an anodic scan. The amount of dissolved Pt2+ below 1.0 V was calculated using collector current (IC) and was confirmed by ex-situ inductively coupled plasma mass spectrometry. The amount of Pt2+ and Pt4+ dissolved in different potential regions during potential cycling was quantified by IC for the first time. A mechanism of Pt dissolution under potential cycling in 0.5 M H2SO4 was proposed, and an in-situ system capable of quantitatively monitoring submonolayer dissolution of Pt2+ and Pt4+ was established.
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