Methanol oxidation catalysts are mainly based on Pt/Pd-based alloys, and various complex strategies are often employed to improve their activity. It is a common practice to clean the contaminants adsorbed on the surface of noble-metal-based catalysts by multiple cyclic voltammetry (MCV) prior to activity test. In this study, we find that this common practice can enhance the activity of noble-metal-based alloy catalysts for methanol oxidation by up to nearly three times. For the first time, a universal criterion is proposed for screening auxiliary metal elements that can significantly improve the activity by this simple practice: oxidable but insoluble in the potential range of CV. Also for the first time, a new activity enhancement mechanism by this common MCV is revealed: noble metal migration, valence state change and oxygen vacancy. As a proof-of-concept, Pt-Sn and Pd-CoSn exhibit high catalytic activity and durability after MCV, making the performance of flexible methanol fuel cells more prominent as well. This work puts forward a universal criterion of auxiliary metal selection and a new mechanism for the remarkably improved activity obtained by MCV, which provides a facile method for obtaining a series of highly active catalysts in the ethaline electrocatalysis field.

甲醇氧化催化剂主要基于 Pt/Pd 基合金，通常采用各种复杂的策略来提高其活性。在活性测试之前，通过多次循环伏安法 (MCV) 清洁吸附在贵金属基催化剂表面的污染物是一种常见的做法。在这项研究中，我们发现这种常见做法可以将贵金属基合金催化剂的甲醇氧化活性提高近三倍。通过这种简单的做法，首次提出了筛选可显着提高活性的辅助金属元素的通用标准：可氧化但不溶于CV电位范围。同样首次揭示了这种常见 MCV 的一种新的活性增强机制：贵金属迁移、价态变化和氧空位。作为概念验证，Pt-Sn 和 Pd-CoSn 在 MCV 之后表现出高催化活性和耐久性，使得柔性甲醇燃料电池的性能也更加突出。该工作提出了一种通用的辅助金属选择标准和MCV显着提高活性的新机制，为在乙醇电催化领域获得一系列高活性催化剂提供了一种简便的方法。