A challenge in the commercialization of proton exchange membrane fuel cells (PEMFC) is the large overpotential for the oxygen reduction reaction (ORR) at the cathode. Platinum is the most active single-component catalyst, but it has the inherent drawbacks of high cost and scarcity. Combining Pt with non-noble metals (eg. Ni, Fe, Cu etc.) has proven to enhance the ORR activity and reduce the Pt mass (1). We describe the use of glancing angle deposition (GLAD, developed by Brett et al. (2), a physical vapor deposition technique) to deposit Ni with controlled nanostructures on glassy carbon supports (Ni GLAD/GC). A unique electrodeposition method was utilized to deposit a thin layer of Pt over the surface of the Ni GLAD structure in a controlled and conformal way. The Pt loading was varied by interrupting the deposition at various coverages, and a series of the Ni GLAD{Pt}/GC deposits was evaluated towards the ORR in acid (3). These Ni GLAD{Pt}/GC deposits are remarkably more active and durable than {Pt}/GC during ORR in acid and in base (4). In addition, dealloying (selective electrodissolution of Ni to make a more robust and active resulting catalytic material) in acid further enhanced the activity of Ni GLAD{Pt}/GC towards the ORR.

Water electrolyzers (WEs) are used to store/transform energy from renewable sources. The sluggish kinetics for the water oxidation reaction (WOR) severely lowers the efficiency of WEs (5). Iridium is an active and stable catalyst for WOR in acid. Due to its high cost, Ir based catalysts with better activity and decreased loading are required for the widespread adoption of WEs. In this talk, we will present a one-pot synthesis of novel highly active and durable Ir-Ni oxide nanoparticles under mild conditions. A mass activity > 140 A g^-1_Ir at 0.25 V overpotential was obtained for IrNi_0.125 atomic composition. Long term galvanostatic polarization and duty cycles showed that the catalysts prepared by this procedure are remarkably stable (6).

References

1.      I. Katsounaros, S. Cherevko, A. R. Zeradjanin and K. J. J. Mayrhofer, Angewandte Chemie International Edition, 53, 102 (2014).

2.      K. Robbie and M. J. Brett, Journal of Vacuum Science & Technology A, 15, 1460 (1997).

3.      C. Wang, R. B. Moghaddam, J. B. Sorge, S. Xu, M. J. Brett and S. H. Bergens, Electrochimica Acta, 176, 620 (2015).

4.      S. Xu, C. Wang, S. A. Francis, R. T. Tucker, J. B. Sorge, R. B. Moghaddam, M. J. Brett and S. H. Bergens, Electrochimica Acta, 151, 537 (2015).

5.      E. Fabbri, A. Habereder, K. Waltar, R. Kotz and T. J. Schmidt, Catalysis Science & Technology, 4, 3800 (2014).

6.      R. B. Moghaddam, C. Wang, J. B. Sorge, M. J. Brett and S. H. Bergens, Electrochemistry Communications, 60, 109 (2015).