Journal of the Korean Electrochemical Society (전기화학회지)

The Korean Electrochemical Society (한국전기화학회)
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Structure Dependent Electrocatalysis for Electroreduction of Oxygen at Nanoporous Gold Surfaces

나노다공성 금 표면상에서 구조 변화에 따른 전기화학적 산소환원 촉매활성

  • Choi, Su-Hee (Department of Chemistry, Chungbuk National University) ;
  • Choi, Kyoung-Min (Department of Chemistry, Chungbuk National University) ;
  • Kim, Jong-Won (Department of Chemistry, Chungbuk National University)
  • Received : 2012.03.06
  • Accepted : 2012.04.13
  • Published : 2012.05.31
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Abstract

We investigate the electrocatalytic activities for oxygen reduction at nanoporous gold (NPG) surfaces fabricated by selective dissolution of Ag from electrodeposited Ag-Au layers on electrode surfaces. The structure of NPG was controlled by changing the concentration ratios of precursor metal complexes during the electrodeposition of Ag-Au layers and the corresponding surface morphology and surface area was examined. NPG structures with Ag/Au ratio of 2.0 exhibited the highest electrocatalytic activity for oxygen reduction, where the nanoporous structure plays a key role, but the surface area does not affect on the electrocatalytic activity. The mechanism of electroreduction of oxygen was investigated by rotating disk electrode techniques. In acidic media, oxygen was first reduced to hydrogen peroxide followed by further reduction to water through 2-step 4-electron mechanism, whereas the oxygen was reduced directly to water by 4-electron mechanism in basic media.

전기화학적 석출에 의해 Ag-Au 합금층을 전극표면에 형성한 후 진한 질산으로 Ag만을 녹여내는 기법으로 나노다공성 금(nanoporous gold, NPG) 구조를 만들어 전기화학적 산소환원에 대한 촉매현상을 관찰하였다. 석출과정의 전구체의 농도비를 달리하였을 때 나타나는 NPG 표면구조의 변화를 주사전자현미경으로 관찰하고 전기화학적 표면적을 측정하였다. 전기화학적 산소환원 촉매 효율은 NPG 표면의 구조에 따라 달라졌는데, Ag/Au 비율이 2.0에 해당하는 NPG 구조에서 가장 우수한 촉매 현상이 관찰 되었다. 표면구조의 변화에 따른 촉매 활성 변화에서 다공성 구조의 역할이 매우 큰 기여를 하는 반면 표면적의 변화는 큰 영향을 미치지 않았다. 최적 조건의 NPG 구조상의 전기화학적 산소환원 과정의 메커니즘을 회전원판전극 실험을 통해 관찰하였는데, 산성 조건에서 NPG 전극에서 전기화학적 산소환원은 과산화수소를 거쳐 물이 생성되는 2-단계 4-전자 환원 메커니즘으로 진행되었고 염기성 조건에서는 산소가 4개의 전자 전달을 통해 물로 직접적으로 환원 되었다.

Keywords

References

  1. M. R. Tarasevich, A. Sadkowski, and E. Yeager, "Oxygen Electrochemistry" in Comprehensive Treatise of Electrochemistry, 301, Plenum, New York (1983).
  2. J. Kim and A. A. Gewirth, 'Mechanism of oxygen electroreduction on gold surfaces in basic media', J. Phys. Chem., B110, 2565 (2006).
  3. R. R. Adzic, N. M. Markovic, and V. B. Vesovic, 'Structural effects in electrocatalysis - oxygen reduction on the Au(100) single-crystal electrode', J. Electroanal. Chem., 165, 105 (1984). https://doi.org/10.1016/S0022-0728(84)80090-X
  4. S. Strbac, N. A. Anastasijevic, and R. R. Adzic, 'Oxygen reduction on Au(100) and vicinal Au(910) and Au(11,1,1) faces in alkaline-solution - A rotating-disk ring study', J. Electroanal. Chem., 323, 179 (1992). https://doi.org/10.1016/0022-0728(92)80010-2
  5. Y. Ding and J. Erlebacher, 'Nanoporous metals with controlled multimodal pore size distribution', J. Am. Chem. Soc., 125, 7772 (2003). https://doi.org/10.1021/ja035318g
  6. A. Wittstock, V. Zielasek, J. Biener, C. M. Friend, and M. Baumer, 'Nanoporous Gold Catalysts for Selective Gas- Phase Oxidative Coupling of Methanol at Low Temperature' Science, 327, 319 (2010). https://doi.org/10.1126/science.1183591
  7. Z. Liu, J. Du, C. Qiu, L. Huang, H. Ma, D. Shen, and Y. Ding, 'Electrochemical sensor for detection of pnitrophenol based on nanoporous gold', Electrochem. Commun., 11, 1365 (2009). https://doi.org/10.1016/j.elecom.2009.05.004
  8. B. Seo and J. Kim, 'Electrooxidation of Glucose at Nanoporous Gold Surfaces: Structure Dependent Electrocatalysis and Its Application to Amperometric Detection', Electroanalysis, 22, 939 (2010). https://doi.org/10.1002/elan.200900514
  9. R. Zeis, T. Lei, K. Sieradzki, J. Snyder, and J. Erlebacher, 'Catalytic reduction of oxygen and hydrogen peroxide by nanoporous gold', J. Catal., 253, 132 (2008). https://doi.org/10.1016/j.jcat.2007.10.017
  10. C. X. Ji and P. C. Searson, 'Synthesis and characterization of nanoporous gold nanowires', J. Phys. Chem., B, 107, 4494 (2003). https://doi.org/10.1021/jp0222200
  11. S. Trasatti and O. A. Petrii, 'Real surface-area measurements in electrochemistry', Pure Appl. Chem., 63, 711 (1991). https://doi.org/10.1351/pac199163050711
  12. M. S. El-Deab and T. Ohsaka, 'An extraordinary electrocatalytic reduction of oxygen on gold nanoparticleselectrodeposited gold electrodes', Electrochem. Commun., 4, 288 (2002). https://doi.org/10.1016/S1388-2481(02)00263-1
  13. M. Hyun, S. Choi, Y. W. Lee, S. H. Kwon, S. W. Han, and J. Kim, 'Simple Electrodeposition of Dendritic Au Rods from Sulfite-Based Au(I) Electrolytes with High Electrocatalytic and SERS Activities', Electroanalysis, 23, 2030 (2011). https://doi.org/10.1002/elan.201000759
  14. A. J. Bard and L. R. Faulkner, Electrochemical Methods, 2nd ed., John Wiley & Sons, New York (2001).
  15. P. R. Birkin, J. M. Elliott, and Y. E. Watson, 'Electrochemical reduction of oxygen on mesoporous platinum microelectrodes', Chem. Commun., 1693 (2000).
  16. S. Tominaka, C.-W. Wu, T. Momma, K. Kurodab, and T. Osaka, 'Perpendicular mesoporous Pt thin films: electrodeposition from titania nanopillars and their electrochemical properties', Chem. Commun., 2888 (2008).
  17. J.-H. Han, E. Lee, S. Park, R. Chang, and T. D. Chung, 'Effect of Nanoporous Structure on Enhanced Electrochemical Reaction', J. Phys. Chem., C114, 9546 (2010).
  18. J. H. Bae, J.-H. Han, and T. D. Chung, 'Electrochemistry at nanoporous interfaces: new opportunity for electrocatalysis', Phys. Chem. Chem. Phys., 14, 448 (2012). https://doi.org/10.1039/c1cp22927c