Facile design of Au@Pt core-shell nanostructures: Formation of Pt submonolayers with tunable coverage and their applications in electrocatalysis
Tóm tắt
A facile design of Pt nanostructures from submonolayer to monolayer has been realized by ion adsorption-in situ electrochemical reduction on Au nanoparticles supported on multiwall carbon nanotubes (CNTs). The as prepared Au@Pt/CNTs catalysts display coverage-specific electrocatalysis. Au@Pt/CNTs with low Pt coverage is inactive towards methanol oxidation whereas it oxidizes formic acid effectively through a direct pathway with mass specific activity 90 times that of a commercial Pt/C catalyst. Due to its inertness to methanol, it shows high performance in the oxygen reduction reaction (ORR) with high methanol tolerance. In contrast, simply increasing the Pt coverage to above 40% switches the formic acid oxidation process to both direct and indirect catalytic pathways, and also results in high methanol oxidation activity.
Tài liệu tham khảo
Steele, B. C.; Heinzel, A. Materials for fuel-cell technologies. Nature 2001, 414, 345–352.
Ji, X.; Lee, K. T.; Holden, R.; Zhang, L.; Zhang, J.; Botton, G. A.; Couillard, M.; Nazar, L. F. Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes. Nat. Chem. 2010, 2, 286–293.
Esposito, D. V.; Chen, J. G. Monolayer platinum supported on tungsten carbides as low-cost electrocatalysts: Opportunities and limitations. Energy Environ. Sci. 2011, 4, 3900–3912.
Sarkar, A.; Manthiram, A. Synthesis of Pt@Cu core-shell nanoparticles by galvanic displacement of Cu by Pt4+ ions and their application as electrocatalysts for oxygen reduction reaction in fuel cells. J. Phys. Chem. C 2010, 114, 4725–4732.
Sasaki, K.; Naohara, H.; Cai, Y.; Choi, Y. M.; Liu, P.; Vukmirovic, M. B.; Wang, J. X.; Adzic, R. R. Core-protected platinum monolayer shell high-stability electrocatalysts for fuel-cell cathodes. Angew. Chem., Int. Ed. 2010, 49, 8602–8607.
Jin, Y.; Shen, Y.; Dong, S. Electrochemical design of ultrathin platinum-coated gold nanoparticle monolayer films as a novel nanostructured electrocatalyst for oxygen reduction. J. Phys. Chem. B 2004, 108, 8142–8147.
Cheng, S.; Rettew, R. E.; Sauerbrey, M.; Alamgir, F. M. Architecture-dependent surface chemistry for Pt monolayers on carbon-supported Au. ACS Appl. Mater. Interfaces 2011, 3, 3948–3956.
Brankovic, S. R.; Wang, J. X.; Adžić, R. R. Metal monolayer deposition by metal adlayers on electrode surface. Surf. Sci. 2001, 474, L173–L179.
Zhang, J.; Mo, Y.; Vukmirovic, M. B.; Klie, R.; Sasaki, K.; Adžić, R. R. Platinum monolayer electrocatalysts for O2 reduction: Pt monolayer on Pd(111) and on carbon-supported Pd nanoparticles. J. Phys. Chem. B 2004, 108, 10955–10964.
Inoue, H.; Brankovic, S. R.; Wang, J. X.; Adžić, R. R. Oxygen reduction on bare and Pt monolayer-modified Ru(0001), Ru(101\(\bar 1\)0) and Ru nanostructured surfaces. Electrochim. Acta 2002, 47, 3777–3785.
Sasaki, K.; Zhang, J.; Wang, J.; Uribe, F.; Adžić, R. R. Platinum submonolayer-monolayer electrocatalysts: An electrochemical and X-ray absorption spectroscopy study. Res. Chem. Intermediat. 2006, 32, 543–559.
Sasaki, K.; Mo, Y.; Wang, J. X.; Balasubramanian, M.; Uribe, F.; McBreen, J.; Adžić, R. R. Pt submonolayers on metal nanoparticles-Novel electrocatalysts for H2 oxidation and O2 reduction. Electrochim. Acta 2003, 48, 3841–3849.
Brankovic, S. R.; Wang, J. X.; Adžić, R. R. Pt submonolayers on Ru nanoparticles: A novel low Pt loading, high CO tolerance fuel cell electrocatalyst. Electrochem. Solid-State Lett. 2001, 4, A217–A220.
Esposito, D. V.; Hunt, S. T.; Kimmel, Y. C.; Chen, J. G. A new class of electrocatalysts for hydrogen production from water electrolysis: Metal monolayers supported on low-cost transition metal carbides. J. Am. Chem. Soc. 2012, 134, 3025–3033.
Nagahara, Y.; Hara, M.; Yoshimoto, S.; Inukai, J.; Yau, S. L.; Itaya, K. In situ scanning tunneling microscopy examination of molecular adlayers of haloplatinate complexes and electrochemically produced platinum nanoparticles on Au(111). J. Phys. Chem. B 2004, 108, 3224–3230.
Kristian, N.; Yu, Y.; Gunawan, P.; Xu, R.; Deng, W.; Liu, X.; Wang, X. Controlled synthesis of Pt-decorated Au nanostructure and its promoted activity toward formic acid electro-oxidation. Electrochim. Acta 2009, 54, 4916–4924.
Hamelin, A. Cyclic voltammetry at gold single-crystal surfaces. J. Electroanal. Chem. 1996, 407, 1–21.
Trasatti, S.; Petrii, O. A. Real surface area measurements in electrochemistry. Pure Appl. Chem. 1991, 63, 711–734.
Kim, S.; Jung, C.; Kim, J.; Rhee, C. K.; Choi, S.-M.; Lim, T. H. Modification of Au nanoparticles dispersed on carbon support using spontaneous deposition of Pt toward formic acid oxidation. Langmuir 2010, 26, 4497–4505.
Zhang, S.; Shao, Y.; Yin, G.; Lin, Y. Electrostatic self-assembly of a Pt-around-Au nanocomposite with high activity towards formic acid oxidation. Angew. Chem., Int. Ed. 2010, 49, 2211–2214.
Capon, A.; Parsons, R. The oxidation of formic acid at noble metal electrodes Part III. Intermediates and mechanism on platinum electrodes. J. Electroanal. Chem. Interfacial Electrochem. 1973, 45, 205–231.
Wolter, O.; Willsau, J.; Heitbaum, J. Reaction pathways of the anodic oxidation of formic acid on Pt evidenced by 18O labeling—A DEMS study. J. Electrochem. Soc. 1985, 132, 1635–1638.
Sun, S. G.; Clavilier, J.; Bewick, A. The mechanism of electrocatalytic oxidation of formic acid on Pt(100) and Pt(111) in sulphuric acid solution: An emirs study. J. Electroanal. Chem. Interfacial Electrochem. 1988, 240, 147–159.
Kristian, N.; Yan, Y.; Wang, X. Highly efficient submonolayer Pt-decorated Au nano-catalysts for formic acid oxidation. Chem. Commun. 2008, 353–355.
Wang, R.; Wang, C.; Cai, W. B.; Ding, Y. Ultralow-platinum-loading high-performance nanoporous electrocatalysts with nanoengineered surface structure. Adv. Mater. 2010, 22, 1845–1848.
Neurock, M.; Janik, M.; Wieckowski, A. A first principles comparison of the mechanism and site requirements for the electrocatalytic oxidation of methanol and formic acid over Pt. Faraday Discuss. 2009, 140, 363–378.