Evaluation of surface oxygen containing species on organically modified Pt electrodes by electrochemical impedance spectroscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K05522
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 34020:Analytical chemistry-related
• Research Institution: Shizuoka University
• Principal Investigator: Miyabayashi Keiko 静岡大学, 工学部, 准教授 (50422663)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 電極触媒 / 酸素還元反応 / 電気化学交流インピーダンス

Outline of Final Research Achievements

By combining the electrochemical impedance spectroscopy (EIS) with the rotating electrode method, oxygen species of surface-modified platinum electrodes were evaluated. We measured the EIS of bulk Pt electrodes at different electrode rotation speeds and found that the double-layer capacitance in the mixed region decreased with increasing rotation speed. In particular, the adsorption of OH species dissociated from water increased below 0.8 V. Measurements at different electrolyte concentrations showed that for the unmodified electrode, the double layer capacitance increased as the electrolyte concentration decreased, and the exponential value of the constant phase element became small, making it more difficult for the reaction substrate to penetrate the electrode surface. However, in the case of a platinum electrode modified with a corrole derivative, the double-layer capacity increased, and the substrate penetration depth did not change depending on electrolyte concentration.

Free Research Field

材料科学

Academic Significance and Societal Importance of the Research Achievements

電極触媒の吸着酸素種の評価は難しく、一般に大型放射光施設での計測が必要である。通常の実験室での測定装置で評価できるようになれば、新規触媒を開発した際に速やかにその影響を評価でき、より高性能触媒の開発を加速化できると考えられる。本研究の成果は、広く普及している電気化学測定装置での測定が可能な電気化学交流インピーダンス法を回転電極法と組み合わせることで、電極表面での酸素種の振舞を捉えるための基礎的知見を得たことである。モデル修飾電極の結果から、電解質濃度を下げても反応基質の侵入深さが変わらず、強酸性や強アルカリ性電解質より中性電解質で表面修飾触媒が活性を示す可能性が示唆された。