Catalytic Activity of Highly Durable Pt/CNT Catalysts Covered with Hydrophobic Silica Layers for the Oxygen Reduction Reaction in PEFCs

• DOI: 10.1021/jp407928m
• Publication Date: 2013-12-26T09:37:47Z
• Authors: Sakae Takenaka; Hiroaki Miyamoto; Yutaka Utsunomiya; Hideki Matsune; Masahiro Kishida
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Carbon nanotube-supported Pt catalysts (Pt/CNT) for the cathode in a polymer electrolyte fuel cell (PEFC) were covered with silica layers using tetraethoxysilane (TEOS) and also methyltriethoxysilane (MTEOS) to improve the catalyst durability under the severe conditions at the PEFC cathode. Both the silica-coated Pt/CNT catalysts had excellent durability for potential cycling between 0.6 and 1.0 V (vs RHE) in N2-purged 0.1 M HClO4 electrolyte, while Pt/CNT without silica coating was significantly deactivated due to an increase of the Pt metal particle size. Silica-coated Pt/CNT prepared from MTEOS had similar activity for the oxygen reduction reaction as Pt/CNT without silica coating, whereas the silica coverage obtained with TEOS slightly reduced the catalytic activity of the Pt/CNT catalyst. The silica layers prepared from MTEOS are more hydrophobic than those prepared from TEOS due to the presence of methyl groups. In addition, the silica layers prepared from MTEOS have larger pores than those prepared...