Improved RhxSy/C Catalyst Structure for Higher HOR/HER Activity

With the development of distributed energy resources such as wind and solar power, there has been growing interest in electrical energy storage. The hydrogen-bromine (H₂-Br₂) reversible fuel cell system serves as one of the promising technologies because of its high round-trip conversion efficiency and low cost. For the highly corrosive HBr/Br₂ environment, alternative catalysts to platinum, which was shown to be rapidly corroded and poisoned in this environment, is needed for the HER/HOR reactions at the hydrogen electrode. Rh_xS_y catalysts have been found to be stable in the HBr/Br₂ environment. Even though existing Rh_xS_y catalysts show high specific HER activity, which makes these catalysts suitable for HBr or HCl electrolysis, their specific HOR activities are not satisfactory for the H₂-Br₂reversible fuel cell system [1, 2]. Recently, we have found a way to develop an optimal RhxSy catalyst structure that results in higher specific HER/HOR activity, as shown in Figure 1. This presentation will discuss the approach used and the characteristics and performance of this catalyst.

References

1. J. Masud, T.V. Nguyen, N. Singh, E. McFarland, M. Ikenberry, K. Hohn, C.J. Pan, and B.J. Hwang, J. Electrochem. Soc., 162 (4) F455-F462 (2015).
2. A. Ivanovskaya, N. Singh, R.F. Liu, H. Kreutzer, J. Baltrusaitis, T.V. Nguyen, H. Metiu, and E. McFarland, Langmuir, 29, 480-492 (2013).

Acknowledgements

The work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000262 and the National Science Foundation under Grant No. EFRI-1038234.