Supportless, Bismuth-Modified Palladium Nanotubes with Improved Activity and Stability for Formic Acid Oxidation

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• 作者：Robert W. Atkinson ; III ; Samuel St. John ; Ondrej Dyck ; Kinga A. Unocic ; Raymond R. Unocic ; Colten S. Burke ; Joshua W. Cisco ; Cynthia A. Rice ; Thomas A. Zawodzinski ; Jr. ; Alexander B. Papandrew
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：September 4, 2015
• 年：2015
• 卷：5
• 期：9
• 页码：5154-5163
• 全文大小：693K
• ISSN：2155-5435

文摘

Palladium nanotubes (PdNTs) were synthesized by templated vapor deposition and investigated for formic acid electrooxidation. Annealed PdNTs are 2.4 times more active (2.19 mA/cm²) than commercial carbon-supported palladium (0.91 mA/cm²) at 0.3 V vs RHE. Bismuth modification improved nanotube performance over 4 times (3.75 mA/cm²) vs Pd/C and nearly 2 times vs unmodified PdNTs. A surface Bi coverage of 80% results in optimal site-specific activity by drastically reducing surface-poisoning CO generation during formic acid electrooxidation. The Bi-modified PdNTs are exceptionally stable, maintaining 2 times the area-normalized current density as Pd/C after 24 h at 0.2 V vs RHE. We attribute the enhanced activity and stability of the nanotube catalysts to the presence of highly coordinated surfaces, mimicking a flat polycrystal while retaining high surface area geometry.