| 학회 | 한국재료학회 |
| 학술대회 | 2017년 가을 (11/15 ~ 11/17, 경주 현대호텔) |
| 권호 | 23권 2호 |
| 발표분야 | 6. 인공광합성 기술 개발 동향(Recent research trends in artificial photo-synthesis) |
| 제목 | Current Challenge in Understanding Water Oxidation Mechanism |
| 초록 | Water splitting is regarded as a promising step towards environmentally sustainable energy schemes because electrolysis produces only hydrogen and oxygen, without any by-products. The oxygen evolution reaction (OER), an anodic half-cell reaction, requires extremely high overpotential due to its slow reaction kinetics. To develop and design efficient water oxidation catalysts for OER, fully understanding the water oxidation mechanism is significantly important which faces a current challenge. In this stream, we made two approaches for better understanding the overall water oxidation mechanism which include 1) Impedance Analysis and 2) Marcus-Hush model study. For the film-type OER electrocatalysts, they exhibits optimum performance at hundreds nanometer thickness. Inside the electrocatalyst film with considerable thickness, not only catalytic reaction, but also various electrochemical phenomena occur. To decouple and interrogate these processes, we conducted advanced electrochemical impedance analysis for MnO nanoparticles film which shows superior OER activity at neutral condition. In the previous study, Cahan and Lyon group performed impedance analysis by simple circuit model to examine only kinetics of catalytic reaction. In this study, we proposed progressive circuit model with infinite RC loops which generally utilized in DSSCs. Therefore, we obtained meaningful parameters to demonstrate overall OER scheme in the film-type OER electrocatalysts. Also, Butler-Volmer model is widely used for measuring catalytic activity and mechanistic analysis based on the value of transfer coefficient (α). Nevertheless, the model is limited to explain molecular nature of the electroactive species, solvent and the electrode in reaction system. In order to redeem these limitations, we tried to apply the Marcus-Hush model for interpreting our OER system, using new parameters to describe physical properties such as reorganization energy (λ) and asymmetric factor (γ). As a result, the Marcus-Hush model was well fitted over a wide potential range. Also, we calculated the reorganization energy for OER kinetics on the MnO NPs that is well matched with the fitting value. In this regard, we believe that the analysis with Marcus-Hush model is attributed to the understanding for molecular behavior during electrocatalysis. |
| 저자 | 남기태 |
| 소속 | 서울대 |
| 키워드 | <P>Water Splitting; Electrocatalysts; Water Oxidation Mechanism</P> |
