Preparation of Carbon Nanotube-Supported Pt Metal Particles Covered with Silica Layers and Their Application to Electrocatalysts for PEMFC

Abstract

Carbon nanotube (CNT)-supported Pt metal nanoparticles were covered with silica layers by hydrolysis of 3-aminopropyl-triethoxysilane (APTES) and/or tetraethoxysilane (TEOS). The hydrolysis of only APTES resulted in a uniform coverage of silica layers on Pt/CNT, but the thickness of the silica layers was very thin (\1 nm). Pt/CNT could also be coated with silica layers of a few nanometers in thickness by hydrolysis of TEOS, but exposed surfaces of CNTs in the sample were frequently observed. In contrast, the successive hydrolysis of APTES and TEOS brought about a uniform coverage of silica layers of a few nanometers in thickness on Pt/CNT. The silica-coated Pt/CNT showed high catalytic activity for electrochemical reactions in aqueous H 2 SO 4 electrolyte, in spite of a uniform coverage of Pt metal with silica layers. In addition, the coverage of Pt/CNT with silica layers improved its durability in electrochemical reactions.

Design of a core–shell Pt–SiO2 catalyst in a reverse microemulsion system: Distinctive kinetics on CO oxidation at low temperature

“…Core-shell catalysts that consist of active metal particles surrounded by porous oxides have drawn much attention because of their enhanced catalytic activity and stability in water-gas shift reactions [1][2][3], dry reforming of methane [4][5][6][7][8][9], hydrocarbon oxidation [10], electrocatalysis [11][12][13][14][15][16], photocatalytic water splitting [17,18], and hydrogenation reactions [19][20][21]. A water-in-oil reverse microemulsion system consists of thermodynamically stable nanosized aqueous micelles surrounded by self-assembled surfactant dispersed in an organic solvent [22].…”

Selective Confinement of Ruthenium Nanoparticles in Silica Nanotubes

“…Pt/CNTs were covered with silica layers by hydrolysis of 3‐aminopropyltriethoxysilane and/or tetraethoxysilane (TEOS). The silica‐coated Pt/CNT showed high catalytic activity for electrochemical reactions in aqueous H 2 SO 4 electrolyte, despite the uniform coverage of the Pt metal with silica layers 10. Pt/CNT11 and PtAu/CNT12 catalysts were covered by a porous SiO 2 layer to improve their thermal and electrochemical stability.…”

C-SiO2 Supported Catalysts for Durability and Performance Improvement in PEM Fuel Cells

“…Takenaka et al used silica coated carbon nanotube (CNT) as support material and reported that silica-coating improved the durability of Pt/CNT electrocatalysts (22). Although it has negatively affected the conductivity and hydrophobicity of the catalyst layer, Travitsky et al used SiO 2 as a support material (23).…”