The widespread use of metal-air batteries for mobile applications will require reduced Pt loading and enhanced catalytic activity within their cathodes to drive the sluggish oxygen reduction reaction (ORR). Despite tremendous efforts, however, elegant bottom-up synthesis of practical nanomaterials remains highly challenging. Here, we propose “in-situ observation” as a novel descriptor to nicely bridge the adsorbates coverage and the oxygen reduction activity of Pt-based catalysts. In-situ X-ray powder diffraction characterization directly observed the ORR process and the evident change of the (111) peak intensity shows continuous oxygen adsorption on the catalyst surface. As expected, the catalyst exhibiting the greatest intensity change delivers the best oxygen reduction activity with a half-wave potential of 0.92 V versus reversible hydrogen electrode and an excellent bifunctional performance with a small potential difference of 0.75 V. Once assembled as the cathode catalyst, both aqueous and all-solid-state zinc-air battery illustrate high power density and superior cycling stability, holding great potential as a novel energy supply for wearable electronics. The cutting-edge in-situ observation is thus identified as a valid activity descriptor to guide less empirical synthesis of enhanced ORR electrocatalysts.

金属空气电池在移动应用中的广泛使用将需要减少Pt的负载并增强其阴极内的催化活性，以驱动缓慢的氧还原反应（ORR）。尽管付出了巨大的努力，但是，实用的纳米材料自下而上的优雅合成仍然具有很高的挑战性。在这里，我们提出“原位观察”作为新颖的描述符，以很好地桥接Pt基催化剂的吸附物覆盖率和氧还原活性。原位X射线粉末衍射表征直接观察到ORR过程，并且（111）峰强度的明显变化表明催化剂表面上连续的氧吸附。正如预期的那样，与可逆氢电极相比，表现出最大强度变化的催化剂具有最佳的氧还原活性，半波电势为0.92 V，具有出色的双功能性能，电势差为0.75V。组装成阴极催化剂后，水性和全固态锌空气电池均显示出高功率密度和出色的循环稳定性，作为可穿戴电子设备的新型能源具有巨大的潜力。尖端的原位 因此，将观察到的现象鉴定为有效的活性描述符，以指导较少的经验性合成增强的ORR电催化剂。