Wang Min, Meng Andrew C, Fu Jintao, Foucher Alexandre C, Serra-Maia Rui, Stach Eric A, Detsi Eric, Pikul James H
Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
ACS Appl Mater Interfaces. 2021 Mar 24;13(11):13097-13105. doi: 10.1021/acsami.0c20163. Epub 2021 Mar 14.
The performance of metal-air batteries and fuel cells depends on the speed and efficiency of electrochemical oxygen reduction reactions at the cathode, which can be improved by engineering the atomic arrangement of cathode catalysts. It is, however, difficult to improve upon the performance of platinum nanoparticles in alkaline electrolytes with low-loading catalysts that can be manufactured at scale. Here, the authors synthesized nanoporous gold catalysts with increased (100) surface facets using electrochemical dealloying in sodium citrate surfactant electrolytes. These modified nanoporous gold catalysts achieved an 8% higher operating voltage and 30% greater power density in aluminum-air batteries over traditionally prepared nanoporous gold, and their performance was superior to commercial platinum nanoparticle electrodes at a 10 times lower mass loading. The authors used rotation disc electrode studies, backscattering of electrons, and underpotential deposition to show that the increased (100) facets improved the catalytic activity of citrate dealloyed nanoporous gold compared to conventional nanoporous gold. The citrate dealloyed samples also had the highest stability and least concentration of steps and kinks. The developed synthesis and characterization techniques will enable the design and synthesis of metal nanostructured catalysts with controlled facets for low-cost and mass production of metal-air battery cathodes.
金属空气电池和燃料电池的性能取决于阴极处电化学氧还原反应的速度和效率，通过设计阴极催化剂的原子排列可以提高该反应的速度和效率。然而，对于可规模化制造的低负载催化剂，在碱性电解质中很难提高铂纳米颗粒的性能。在此，作者在柠檬酸钠表面活性剂电解质中通过电化学脱合金法合成了具有更多（100）表面晶面的纳米多孔金催化剂。与传统制备的纳米多孔金相比，这些改性纳米多孔金催化剂在铝空气电池中实现了高8%的工作电压和高30%的功率密度，并且在质量负载低10倍的情况下，其性能优于商业铂纳米颗粒电极。作者使用旋转圆盘电极研究、电子背散射和欠电位沉积表明，与传统纳米多孔金相比，增加的（100）晶面提高了柠檬酸盐脱合金纳米多孔金的催化活性。柠檬酸盐脱合金样品还具有最高的稳定性以及最少的台阶和扭结浓度。所开发的合成和表征技术将能够设计和合成具有可控晶面的金属纳米结构催化剂，以低成本大规模生产金属空气电池阴极。
