• DOI:10.1039/c6nr01112h
• Corpus ID: 11306008

Structural dynamics and activity of nanocatalysts inside fuel cells by in operando atomic pair distribution studies.

@article{Petkov2016StructuralDA,
  title={Structural dynamics and activity of nanocatalysts inside fuel cells by in operando atomic pair distribution studies.},
  author={Valeri Petkov and Binay Prasai and Shiyao Shan and Yang Ren and Jinfang Wu and Hannah Cronk and Jin Luo and Chuan-Jian Zhong},
  journal={Nanoscale},
  year={2016},
  volume={8 20},
  pages={
          10749-67
        }
}

• V. Petkov, B. Prasai, +5 authors C. Zhong
• Published 19 May 2016
• Biology
• Nanoscale

Here we present the results from a study aimed at clarifying the relationship between the atomic structure and activity of nanocatalysts for chemical reactions driving fuel cells, such as the oxygen reduction reaction (ORR). In particular, using in operando high-energy X-ray diffraction (HE-XRD) we tracked the evolution of the atomic structure and activity of noble metal-transition metal (NM-TM) nanocatalysts for ORR as they function at the cathode of a fully operational proton exchange membrane fuel cell (PEMFC). Experimental HE-XRD data were analysed in terms of atomic pair distribution functions (PDFs) and compared to the current output of the PEMFC, which was also recorded during the experiments. The comparison revealed that under actual operating conditions, NM-TM nanocatalysts can undergo structural changes that differ significantly in both length-scale and dynamics and so can suffer losses in their ORR activity that differ significantly in both character and magnitude. Therefore we argue that strategies for reducing ORR activity losses should implement steps for achieving control not only over the length but also over the time-scale of the structural changes of NM-TM NPs that indeed occur during PEMFC operation. Moreover, we demonstrate how such a control can be achieved and thereby the performance of PEMFCs improved considerably. Last but not least, we argue that the unique capabilities of in operando HE-XRD coupled to atomic PDF analysis to characterize active nanocatalysts inside operating fuel cells both in a time-resolved manner and with atomic level resolution, i.e. in 4D, can serve well the ongoing search for nanocatalysts that deliver more with less platinum.