Investigation of hydrogen superoxide adsorption during ORR on Pt/C catalyst in acidic solution for PEFC by high energy resolution XAFS

山本 直生*; 松村 大樹; 萩原 悠人*; 田中 啓偉*; 長谷川 優太*; 石井 賢司*; 田中 裕久*

Journal of Power Sources, 557, p.232508_1 - 232508_10, 2023/02

https://doi.org/10.1016/j.jpowsour.2022.232508

Oxygen Reduction Reaction (ORR) is one of the key electrochemical reactions, especially in Polymer Electrolyte Fuel Cells (PEFCs). In this work, the reaction pathway and intermediate species such as molecular-type oxygen during ORR were discussed. High energy resolution X-ray absorption fine structure spectra at the Pt L-edge were obtained to observe the electronic structure of Pt catalyst. Carbon-supported Pt nanoparticles as powder catalysts were used for measurement as more realistic conditions, and the species adsorbed on the Pt nanoparticles were analyzed while controlling under the potentials in acidic electrolyte solution with N or O gas bubbling. Molecular-type oxygen adsorption species is observed only in the O-bubbled electrolyte solution. This intermediate adsorption species is assigned to a hydrogen superoxide.

Activity enhancement of platinum oxygen-reduction electrocatalysts using ion-beam induced defects

木全 哲也*; 垣谷 健太*; 山本 春也*; 下山 巖; 松村 大樹; 岩瀬 彰宏*; Mao, W.*; 小林 知洋*; 八巻 徹也*; 寺井 隆幸*

Physical Review Materials (Internet), 6(3), p.035801_1 - 035801_7, 2022/03

https://doi.org/10.1103/PhysRevMaterials.6.035801

High activity is one of the primary requirements for the catalysts in proton exchange membrane fuel cell applications. Previous computational studies suggested that the catalytic activity of Pt nanoparticles could be enhanced by a Pt-carbon (C) support interaction. We have recently found that an enhanced electronic interaction occurs at the interface between an argon-ion (Ar)-irradiated glassy carbon (GC) surface and Pt nanoparticles. Here, we report a more than two-fold increase in specific activity (SA) for the Pt nanoparticles on the Ar-irradiated GC substrate compared to that on the non-irradiated GC substrate. The mechanism of this activity enhancement was investigated by local structure analysis of the interface. Ar irradiation of the carbon support led to the formation of the Pt-C bonding, thus protecting the deposited Pt nanoparticles from oxidation.

In situ XAFS and HAXPES analysis and theoretical study of cobalt polypyrrole incorporated on carbon (CoPPyC) oxygen reduction reaction catalysts for anion-exchange membrane fuel cells

朝澤 浩一郎*; 岸 浩史*; 田中 裕久*; 松村 大樹; 田村 和久; 西畑 保雄; Saputro, A. G.*; 中西 寛*; 笠井 秀明*; Artyushkova, K.*; et al.

Journal of Physical Chemistry C, 118(44), p.25480 - 25486, 2014/11

https://doi.org/10.1021/jp507534f

Non-noble metal electrocatalysts not only are a solution to limited resources but also achieve higher efficiency for fuel cells, especially in alkaline media such as alkaline membrane fuel cells. Co-polypyrrole-based electrocatalysts provide high oxygen reduction reaction (ORR) reactivity, but the active sites and reaction mechanism have yet to be elucidated fully. In this study, ex situ and in situ synchrotron characterization and theoretical study have been combined to evaluate the ORR mechanism on two possible active sites consisting of Co coordinated with pyrrolic nitrogen and Co coordinated with pyridinic nitrogen.

腐食メカニズムに基づく炭素鋼オーバーパックの腐食モデル開発(I)

本田 明; 井上 邦博*; 小畑 政道*

PNC TN8410 93-299, 26 Pages, 1993/12

PNC-TN8410-93-299.pdf:0.81MB

高レベル放射性廃棄物の地層処分における人工バリアシステムの構成要素であるオーバーパックの腐食挙動を評価するために、腐食メカニズムに基づく腐食挙動評価モデルを開発している。本資料は、現状での炭素鋼オーバーパックの腐食挙動評価モデルの構成と評価例についてまとめたものである。全面腐食については、金属表面での電気化学反応速度と溶存酸素の輸送を考慮したモデルを開発した。このモデルでは皮膜の効果を無視するという保守的な仮定を置いていることから1000年で74mmという過大な腐食量が算定された。また局部腐食が進展しうるのは不動態保持電流以上のカソード電流が酸素還元反応によって供給されうる期間であるとして、局部腐食が進展しうる期間を、ベントナイト中の酸素の輸送に基づき評価した。その結果、局部腐食が実質的に進展しうるのは、ベントナイトが地下水で飽和されるまでの期間と考えられた。開発中の局部腐食進展モデルについては、その構成について示した。