Advances in Ptni Nanowire Extended Thin Film Electrocatalysts

Fuel cells offer tremendous promise in pushing society towards a more sustainable energy system by enabling the production of renewable fuels with zero criteria pollutant emissions. One key barrier for such a future energy system for fuel cell adoption s the need for platinum group metals for catalysis and the quantities required for efficient performance. It has been a long-standing goal to continually increase performance and durability of electrochemical devices, and one promising approach has been the development and implementation of extended thin film electrocatalysts. 1 Our team has extensively investigated extended surface catalysts as a novel platform for increased performance and durability at lower cost. 2,3,4 This presentation will highlight the advances of our team in the synthesis and implementation of extended surface electrocatalysts with a focus on PtNi nanowires (NWs) produced by atomic layer deposition (ALD) . We have demonstrated the ability to obtain high performance PtNi NWs following ALD deposition by a series of steps that include annealing under reducing conditions and acid leaching. This results in high activity and surface area catalyst that have limited Ni remaining, thereby mitigating issues of potential Ni contamination when assembled into MEAs. These catalysts have been incorporated into fuel cells investigating several different processing variables including catalyst loading, ionomer to catalyst ratio, and inclusion of carbon. Through optimization efforts, we have been able to achieve mass activities that surpass US Department of Energy targets for both performance and durability as demonstrated in Figure 1. These results have started to show the potential of extended surface electrocatalysts in cell testing. This presentation will discuss the factors that have allowed these performances to be achieved and future work to further advance both the inherent electrochemical properties of these catalysts and also the MEA performance of fuel cells based on these materials. Figure 1. Polarization curves for PtNiNW based on initial cell performance and after 5,000 cycles of carbon corrosion testing. Mark K. Debe∗, Alison K. Schmoeckel, George D. Vernstrom, Radoslav Atanasoski, Journal of Power Sources 161 (2006) 1002–1011. Shaun Alia, Svitlana Pylypenko, Arrelaine Dameron, KC Neyerlin, Shyam Kocha, Bryan Pivovar, J. Electrochem. Soc. 2016 163(3): F296-F301. Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, Shyam S. Kocha, and Bryan S. Pivovar, J. Electrochem. Soc. 2015 162(12): F1299-F1304. Shaun M. Alia, Svitlana Pylypenko, K.C. Neyerlin, David A. Cullen, Shyam S. Kocha, Bryan S. Pivovar, ACS Catalysis, 4, 2680, 2014. Figure 1