Department of Chemistry and Chemical Biology, Northeastern University , Boston, Massachusetts 02115, United States.
Shanghai Electrochemical Energy Devices Research Center, Department of Chemical Engineering, Shanghai Jiao Tong University , Shanghai 200240, China.
J Am Chem Soc. 2017 Feb 1;139(4):1384-1387. doi: 10.1021/jacs.6b11072. Epub 2017 Jan 18.
Proper understanding of the major limitations of current catalysts for oxygen reduction reaction (ORR) is essential for further advancement. Herein by studying representative Pt and non-Pt ORR catalysts with a wide range of redox potential (E) via combined electrochemical, theoretical, and in situ spectroscopic methods, we demonstrate that the role of the site-blocking effect in limiting the ORR varies drastically depending on the E of active sites; and the intrinsic activity of active sites with low E have been markedly underestimated owing to the overlook of this effect. Accordingly, we establish a general asymmetric volcano trend in the ORR activity: the ORR of the catalysts on the overly high E side of the volcano is limited by the intrinsic activity; whereas the ORR of the catalysts on the low E side is limited by either the site-blocking effect and/or intrinsic activity depending on the E.
正确理解当前氧还原反应（ORR）催化剂的主要局限性对于进一步的发展至关重要。在此，通过结合电化学、理论和原位光谱方法研究具有广泛氧化还原电位（E）的代表性 Pt 和非 Pt ORR 催化剂，我们证明了位阻效应在限制 ORR 方面的作用随活性位的 E 而剧烈变化；并且由于忽略了这种效应，低 E 的活性位的本征活性被明显低估。因此，我们建立了一个普遍的不对称火山形 ORR 活性趋势：在火山形的过高 E 侧的催化剂的 ORR 受到本征活性的限制；而在低 E 侧的催化剂的 ORR 受到位阻效应和/或本征活性的限制，具体取决于 E。
