State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin China.
Shandong Provincial Key Laboratory of Fluorine Chemical Materials, School of Chemistry and Chemical Engineering, University of Jinan , Jinan 250022, Shandong, China.
Anal Chem. 2017 Jun 20;89(12):6309-6313. doi: 10.1021/acs.analchem.7b01507. Epub 2017 Jun 5.
An in situ micro-MEA technique, which could precisely measure the performance of ORR electrocatalyst using Nafion as electrolyte, was designed and compared with regular thin-film rotating-disk electrode (TFRDE) (0.1 M HClO) and normal in situ membrane electrode assembly (MEA) tests. Compared to the traditional TFRDE method, the micro-MEA technique makes the acquisition of catalysts' behavior at low potential values easily achieved without being limited by the solubility of O in water. At the same time, it successfully mimics the structure of regular MEAs and obtains similar results to a regular MEA, thus providing a new technique to simply measure the electrode activity without being bothered by complicated fabrication of regular MEA. In order to further understand the importance of in situ measurement, Fe-N-C as a typical oxygen reduction reaction (ORR) free-Pt catalyst was evaluated by TFRDE and micro-MEA. The results show that the half wave potential of Fe-N-C only shifted negatively by -135 mV in comparison with state-of-the-art Pt/C catalysts from TFRDE tests. However, the active site density, mass transfer of O, and the proton transfer conductivity are found to strongly influence the catalyst activity in the micro-MEA, thereby resulting in a much lower limiting current density than Pt/C (8.7 times lower). Hence, it is suggested that the micro-MEA is better in evaluating the in situ ORR performance, where the catalysts are characterized more thoroughly in terms of intrinsic activity, active site density, proton transfer, and mass transfer properties.
一种原位微-MEA 技术被设计出来，可以使用 Nafion 作为电解质精确测量 ORR 电催化剂的性能，并与常规的薄膜旋转圆盘电极 (TFRDE) (0.1 M HClO) 和常规原位膜电极组件 (MEA) 测试进行比较。与传统的 TFRDE 方法相比，微-MEA 技术使得在不受到水中 O 溶解度限制的情况下，很容易获得催化剂在低电位下的行为。同时，它成功地模拟了常规 MEA 的结构，并获得了与常规 MEA 相似的结果，从而提供了一种简单测量电极活性的新技术，而不必受到常规 MEA 复杂制造的困扰。为了进一步了解原位测量的重要性，采用 TFRDE 和微-MEA 对 Fe-N-C 作为典型的氧还原反应 (ORR) 无 Pt 催化剂进行了评估。结果表明，与 TFRDE 测试中的先进 Pt/C 催化剂相比，Fe-N-C 的半波电位仅负移了-135 mV。然而，发现活性位密度、O 的传质和质子传递电导率强烈影响微-MEA 中的催化剂活性，从而导致比 Pt/C 低得多的极限电流密度 (低 8.7 倍)。因此，建议使用微-MEA 更好地评估原位 ORR 性能，在原位 ORR 性能中，催化剂可以更全面地从内在活性、活性位密度、质子传递和质量传递特性方面进行表征。
