Lönn Björn, Strandberg Linnéa, Roth Vera, Luneau Mathilde, Wickman Björn
Chemical Physics, Department of Physics, Chalmers University of Technology, Gothenburg 412 96, Sweden.
Competence Centre for Catalysis, Chalmers University of Technology, Gothenburg 412 96, Sweden.
ACS Omega. 2024 Oct 17;9(43):43725-43733. doi: 10.1021/acsomega.4c06245. eCollection 2024 Oct 29.
Platinum (Pt) nanoparticles are widely used as catalysts in proton exchange membrane fuel cells. In recent decades, sputter deposition onto liquid substrates has emerged as a potential alternative for nanoparticle synthesis, offering a synthesis process free of contaminant oxygen, capping agents, and chemical precursors. Here, we present a method for the synthesis of supported nanoparticles based on magnetron sputtering onto liquid poly(ethylene glycol) (PEG) combined with a heat-treatment step for attachment of nanoparticles to a carbon support. Transmission electron microscopy imaging reveals Pt nanoparticle growth during the heat-treatment process, facilitated by the carbon support and the reducing properties of PEG. Following the heat treatment, a bimodal size distribution of Pt nanoparticles is observed, with sizes of 2.5 ± 0.8 and 6.7 ± 1.8 nm, compared to 1.8 ± 0.4 nm after sputtering. Synthesized Pt nanoparticles display excellent specific and mass activities for the oxygen reduction reaction, with 1.75 mA/cm and 0.27 A/mg respectively, measured at 0.9 V vs the reversible hydrogen electrode. The specific activities reported herein outperform literature values of commercial Pt/C catalysts with similar loading and are on par with values of bulk Pt and mass-selected nanoparticles of comparable size. Also, the mass activities agree well with the literature values. The results provide new insights into the growth processes of SoL-synthesized carbon-supported Pt catalyst nanoparticles, and most crucially, the high performance of the synthesized catalyst layers, along with the possibility of nanoparticle growth through a straightforward heat-treatment step at relatively low temperatures, offer a scalable new approach for producing fuel cell catalysts with more efficient material utilization and new material combinations.
铂（Pt）纳米颗粒被广泛用作质子交换膜燃料电池中的催化剂。近几十年来，在液体基底上进行溅射沉积已成为纳米颗粒合成的一种潜在替代方法，该方法提供了一种不含污染性氧气、封端剂和化学前驱体的合成过程。在此，我们提出一种基于磁控溅射在液体聚乙二醇（PEG）上合成负载型纳米颗粒的方法，并结合一个热处理步骤，以使纳米颗粒附着到碳载体上。透射电子显微镜成像揭示了在热处理过程中铂纳米颗粒的生长情况，这一过程由碳载体和PEG的还原特性所促进。热处理后，观察到铂纳米颗粒呈现双峰尺寸分布，尺寸分别为2.5±0.8纳米和6.7±1.8纳米，而溅射后为1.8±0.4纳米。合成的铂纳米颗粒对氧还原反应显示出优异的比活性和质量活性，在相对于可逆氢电极0.9伏的条件下测量，分别为1.75毫安/平方厘米和0.27安/毫克。本文报道的比活性优于具有相似负载量的商业铂/碳催化剂的文献值，与块状铂以及尺寸相当的质量选择纳米颗粒的值相当。此外，质量活性与文献值也吻合得很好。这些结果为溶液合成的碳负载铂催化剂纳米颗粒的生长过程提供了新的见解，最关键的是，合成催化剂层的高性能，以及通过在相对较低温度下直接热处理步骤实现纳米颗粒生长的可能性，为生产具有更高效材料利用率和新型材料组合的燃料电池催化剂提供了一种可扩展的新方法。
