Oxygen reduction reaction catalyst

Proton-exchange membrane fuel cell (PEMFC) is one of the promising green energy storage and conversion devices. However, the current PEMFC requires high-cost Pt/C catalysts, which hinders its commercial progress. The aim of this project is developing a type of low-cost non-precious metal catalysts (NPMCs) for the crucial component PEMFC, i.e., cathodic electrocatalytic oxygen reduction reaction (ORR).

TEM

We have prepared a series of carbon film encapsulated Fe (CF-Fe) NPMCs by a home-made high-pressure pyrolysis setup with controlling the temperature and time. The as-prepared CF-Fe catalyst shows a high onset potential (0.87 V) and half-wave potentials (0.72 V) (versus revisable hydrogen electrode, RHE) and high stability (~25 mV shift after 10,000 cycles) in acid media. These performances are close to those of Pt/C catalyst and even more exhibit improved stability. In addition, we further demonstrated the complex components for the CF-Fe catalysts by virtue of the X-ray diffraction and 57Fe-Mössbauer spectra, which includes α-Fe, γ-Fe, Fe3N, FeIIN4/C (low spin) and Fe3C. Through active-site investigation, we further demonstrated that ORR activity parameters involving half-wave potential, Tafel slope and kinetic current density were positively related with content of Fe3C and FeIIN4/C, which indicates the active components. Overall, our results offer a new type of highly-efficient iron-based NPMCs and identified the components and active sites. The further work will be devoted to establishing the practical PEMFC device by the as-preared catalysts.

Voltammetry

Dissemination activties

  • Electrolysis & Fuel Cell Discussions –challenges towards zero platinum for oxygen reduction, 13-16 September, La Grande Motte, France (Poster).
  • International conference on innovation electrochemical energy materials and technologies, 8-11 November, Guangxi university China (Oral presentation)

Contact

http://www.4m-centre.dk/Research/lijie-zhong
23 JULY 2017