高性能自支撑氧催化电极基底材料的研究进展

在“碳达峰”和“碳中和”的时代背景下，电解水、金属空气电池、燃料电池等清洁能源技术由于具有能量效率高、安全性好、结构简单和清洁环保等优点受到广泛关注。然而，发生在氧催化电极上的关键反应——氧还原反应（ORR）和氧析出反应（OER）具有缓慢的动力学，很大程度上阻碍了其商业化应用。传统氧催化电极存在合成过程繁琐、可控性低、均一性差、成本高和载体催化剂易团聚等问题，限制了其催化性能。自支撑氧催化电极的高催化活性位点、高稳定性等优势可以完美解决传统电极面临的问题。本文介绍了自支撑氧催化电极基底材料的研究进展以及合成方法，并讨论了影响自支撑氧催化电极ORR/OER催化性能的因素，最后对自支撑氧催化电极未来的研发方向和发展趋势提出展望。 

Substrate materials for high performance self-supporting oxygen catalytic electrodes

Under the background of peak carbon dioxide emissions and achieving carbon neutrality, clean energy technologies such as water electrolysis, metal–air batteries, and fuel cells have attracted extensive attention due to the advantages of high efficiency, good safety, a simple structure, low cost, and eco-friendliness. However, the key reactions on oxygen catalytic electrodes, the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are kinetically sluggish, which considerably hinders their commercial applications. The traditional oxygen catalytic electrodes with the use of binders have the disadvantages of a cumbersome synthesis process, low controllability, poor uniformity, high cost, and easy carrier catalyst agglomeration, which limit their catalytic performance. Recently, self-supported oxygen catalytic electrodes have attracted extensive attention due to their advantages of high catalytic active sites and a stabilized spatial framework, which can solve the problems faced by traditional oxygen catalytic electrodes and further improve the catalytic performance of the electrode. As the catalyst material carrier, the substrate materials play an important role in the catalytic performance of self-supporting oxygen electrodes. The high interaction forces between the substrate and the catalyst material lead to a single-direction growth orientation and uniform dispersion. Reportedly, the substrate materials for self-supporting oxygen catalytic electrodes have not been fully discussed in comprehensive reviews. Therefore, timely updates in this potential field must be provided. This paper summarizes the research progress and synthesis methods of commonly self-supporting oxygen catalytic electrodes based on different substrate materials, including two- and three-dimensional metal materials and carbon materials. In addition, this paper introduces the outstanding ORR/OER catalytic properties of common self-supporting oxygen catalytic electrodes, which are not only due to the intrinsic catalytic activity of the supported catalytic active materials but also related to the high specific surface area and high electron transfer rate caused by the structure of the self-supported electrode substrate. Finally, the future research and the development trend of self-supporting oxygen catalytic electrodes are addressed from the four aspects of density general function theory, improving electrode energy density, constructing an efficient gas–liquid–solid three-phase interface of an electrode, and establishing a standard evaluation protocol of self-supported oxygen catalytic electrodes. This review should provide new research insights for developing renewable energy storage and conversion systems.