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Supported Noble Metals on Hydrogen‐Treated TiO 2 Nanotube Arrays as Highly Ordered Electrodes for Fuel Cells
Author(s) -
Zhang Changkun,
Yu Hongmei,
Li Yongkun,
Gao Yuan,
Zhao Yun,
Song Wei,
Shao Zhigang,
Yi Baolian
Publication year - 2013
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200828
Subject(s) - catalysis , materials science , electrochemistry , electrode , chemical engineering , reversible hydrogen electrode , x ray photoelectron spectroscopy , hydrogen , noble metal , metal , inorganic chemistry , nanotechnology , working electrode , chemistry , organic chemistry , metallurgy , engineering
Hydrogen‐treated TiO 2 nanotube (H–TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H–TNTs increases by approximately one order of magnitude in comparison to air‐treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H–TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H–TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H‐TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H–TNT support. The as‐prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H–TNT‐loaded Pt catalysts that have been annealed in ultrahigh purity H 2 for a second time. There is minimal decrease in the electrochemical surface area of the as‐prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X‐ray photoelectron spectroscopy shows that after the H–TNT‐loaded Pt catalysts are annealed in H 2 for the second time, the strong metal–support interaction between the H–TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel‐cell testing shows that the power density reaches a maximum of 500 mW cm −2 when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra‐low Pt loading, the new electrode generates a specific power density of 2.68 kW g Pt −1 . It is indicated that H–TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports.