산화 이리듐의 물의 산화반응에 대한 버블 과전압 현상과 촉매 특성 연구 = Study on Electrocatalytic Water Oxidation Reaction by Iridium Oxide and Its Bubble Overpotential Effect

다국어 초록 (Multilingual Abstract)

Iridium oxide is well known as an electrocatalyst for the water oxidation. Recently, Dr. Bard's group observed the electrocatalytic behavior of individual nanoparticle of Iridium oxide using the electrochemical amplification method by detecting the single nanoparticle collisions at the ultramicroelectrode (UME). However, the electrocatalytic current is decayed as a function of time. In this study, we investigated that the reason of electrocatalytic current decay of water oxidation at Iridium oxide nanoparticles. We identified it is due to the bubble overpotential because the cyclic current decay and recovery were synchronized to the oxygen bubble growth and coming away from an Iridium disk electrode.

국문 초록 (Abstract)

산화 이리듐은 물의 산화반응에 대해 좋은 전기촉매 물질로서 많은 연구가 이루어 지고 있다. 최근 전기화학적 증폭방법을 이용하여 산화 이리듐 나노입자의 개별적인 촉매특성을 연구한 결과를 보면 촉매반응에 의한 전류가 지속적으로 유지되지 않고 시간에 따라 감소하는 결과가 얻어 졌다. 이러한 촉매특성의 사라짐에 대한 원인을 규명하고자 사이즈가 큰 이리듐전극을 산화시킨 산화이리듐 전극에서 물의 산화반응을 진행시켰다. 그 결과 나노입자에서와 유사하게 전류가 감소하는 현상이 관찰되었다. 큰 전극에서의 실험에서는 발생하는 산소방울을 관찰 할 수 있었는데 산소방울의 발생 주기가 전류의 증감주기와 일치하는 것으로 보아 전류의 감소는 산소방울에 의한 버블 과전압 때문으로 생각된다.

참고문헌 (Reference)

1 T. Nakagawa, "‘Efficient Electro-Oxidation of Water near Its Reversible Potential by a Mesoporous IrOx Nanoparticle Film" 113 : 12958-, 2009

2 J. Eigeldinger, "The bubble coverage of gasevolving electrodes in a flowing electrolyte" 45 : 4449-, 2000

3 S. J. Kwon, "Stochastic electrochemistry with electrocatalytic nanoparticles at inert ultramicroelectrodestheory and experiments" 13 : 5394-, 2011

4 M. Yagi, "Self-assembly of active IrO2 colloid catalyst on an ITO electrode for efficient electrocatalytic water oxidation" 109 : 21489-, 2005

5 C. Gabrielli, "Potential drops due to an attached bubble on a gasevolving electrode" 19 : 617-, 1989

6 M. Hara, "Photocatalytic Water Oxidation in a Buffered Tris(2,2‘-bipyridyl)ruthenium Complex-Colloidal IrO2 System’" 104 : 5275-, 2000

7 X. Xiao, "Observing Single Nanoparticle Collisions at an Ultramicroelectrode by Electrocatalytic Amplification" 129 : 9610-, 2007

8 S. J. Kwon, "Observing Iridium Oxide (IrOx) Single Nanoparticle Collisions at Ultramicroelectrodes" 132 : 13165-, 2010

9 T. Kuwabara, "Characterization and Analysis of Self-Assembly of a Highly Active Colloidal Catalyst for Water Oxidation onto Transparent Conducting Oxide Substrates" 112 : 3774-, 2008

10 P. G. Hoertz, "Bidentate Dicarboxylate Capping Groups and Photosensitizers Control the Size of IrO2 Nanoparticle Catalysts for Water Oxidation" 111 : 6845-, 2007

11 S. J. Kwon, "Analysis of Diffusion- Controlled Stochastic Events of Iridium Oxide Single Nanoparticle Collisions by Scanning Electrochemical Microscopy" 134 : 7102-, 2012