課題番号 ：S-16-KU-0020
利用形態 ：機器利用
利用課題名（日本語） ：新規非白金触媒の開発
Program Title (English) ：Development of novel non-platinum catalysts for fuel cells
利用者名（日本語） ：Jun Yang
Username (English) ：Jun Yang
所属名（日本語） ：九州大学カーボンニュートラル・エネルギー国際研究所
Affiliation (English) ：International Institute for Carbon-Neutral Energy Research, Kyushu University

１．概要（Summary ）
Development of non-platinum electrocatalysts with high performance, durability, and scalability for fuel cells and batteries is a strong social demand for a next-generation eco-friendly energy society. Here, we present a pristine multi-walled carbon nanotube/iron phthalocyanine (MWNT/FePc) hybrid catalyst with a well-defined nanostructure for the oxygen reduction reaction (ORR) in alkaline media that meets this demand. By carefully tuning the microstructure of the FePc stack layer deposited on the highly crystallized graphitic surface of a MWNT support, an ultra-high ORR activity as well as excellent durability are obtained. Moreover, a power density of 185 mW cm−2 at 0.8 V was obtained for a zinc–air battery using this optimized MWNT/FePc cathode at room temperature. Density functional theory-based calculations of such a well-defined nanostructure of MWNT/FePc have suggested that deposition on the bent graphitic surface of MWNTs significantly changes the geometric and electronic structures of FePc that originated from π–π interactions, leading to such enhanced electrocatalytic activity and durability.

２．実験（Experimental）
catalyst is denoted as MWNT/FePc-RE). All products were collected by filtration using a PTFE filter, followed by vacuum drying. The average pore size of PTFE filter was 3 μm (both the as-received MWNTs and FePc particles cannot penetrate through the filter).
The crystal structure was characterized by X-ray diffraction analysis (XRD, SmartLab, Rigaku Corp.). The microstructures of the catalysts were observed using an SU9000 (Hitachi High-Technologies) op-erated at 30 kV. The electron conditions were determined by X-ray photoelectron spectroscopy (XPS, AXIS-ULTRA, Shimazu Corp.). The crystallinity of the MWNTs was evaluated by Raman spectroscopy (533 nm, Raman-touch, Nanophoton Corp.).

３．結果と考察（Results and Discussion）
We successfully established a facile strategy of preparing MWNT/FePc catalysts with a remarkably high activity and durability for the ORR. Moreover, the MWNT/FePc catalyst is easy to form a free-standing electrode film, and the fabricated zinc–air battery exhibited an exceptionally good performance. Compared to other state-of-art FePc-based ORR catalysts, our MWNT/FePc catalyst has a very competitive performance and remarkably high stability while the fabrication procedure is the simplest among the FePc-based catalysts ever reported. Density functional theory-based calculations demonstrated that the geometric and electronic structure of FePc significantly changed when supported on MWNTs, which is responsible for the enhanced electrocatalytic activity and durability. This extremely simple method provides great scalability. We also emphasize that the present method is applicable to the preparation of many catalysts composed of other transition metal phthalocyanines and MWNTs. Such studies are in progress in our laboratory.

４．その他・特記事項（Others）
None
５．論文・学会発表（Publication/Presentation）
(1)J Yang, F Toshimitsu, Z Yang, T Fujigaya, N Nakashima, J. Mater. Chem. A, 2017, 5, 1184-1191.

６．関連特許（Patent）
None