(353b) A Highly Efficient Fe-Rich Confined Catalyst within Layered Zirconium Phosphate for the Oxygen Evolution Reaction in Alkaline Media
AIChE Annual Meeting
Tuesday, November 12, 2019 - 12:48pm to 1:06pm
In this study, we improved the performance of mono-metal adsorbed systems through the ion-exchange of Ni and Fe cations to produce an adsorbed Fe-rich catalyst. The activity and stability of the Fe-rich catalyst was further enhanced via intercalation into the ZrPOx layers. Improved stability by 2-3 orders of magnitude and a reduced overpotential at 10 mA cm-2 by ~200 mV is obtained at an intercalated composition of Ni0.1Fe0.9 versus the adsorbed counterpart. We have demonstrated that the Ni-Fe within the interlayer is an available active site by blocking the surface Ni-Fe sites through a grafting study. After blocking the surface Ni-Fe sites with octadecyl isocyanate, the NiII/NiIII redox feature remains apparent suggesting electrochemical accessibility throughout the layers. To probe the origin of the Ni-Fe activity enhancement via intercalation we characterized the crystal structure, conductivity, electrochemical surface area, oxidation state, morphology, and performance as a function of Ni-Fe composition. Furthermore, OER activities of adsorbed and intercalated Fe and co-intercalated Ni-Fe are assessed by density functional theory calculations to provide atomic-level insights and provide evidence of the stability of zirconium phosphate under the OER in alkaline conditions. In short, a compositional-structural-activity dependence is presented for Ni-Fe zirconium phosphate. The data suggests that the improved activity and stability of an intercalated Ni0.1Fe0.9 system stems from the confined environment provided by the layered structure of zirconium phosphate.
(1) Ursua, A.; Gandia, L. M.; Sanchis, P. Hydrogen Production From Water Electrolysis: Current Status and Future Trends. Proc. IEEE 2012, 100 (2), 410â426.
(2) Xu, D.; Stevens, M. B.; Cosby, M. R.; Oener, S. Z.; Smith, A. M.; Enman, L. J.; Ayers, K. E.; Capuano, C. B.; Renner, J. N.; Danilovic, N.; et al. Earth-Abundant Oxygen Electrocatalysts for Alkaline Anion-Exchange-Membrane Water Electrolysis: Effects of Catalyst Conductivity and Comparison with Performance in Three-Electrode Cells. ACS Catal. 2018, 7â15.
(3) Wei Seh, Z.; Kibsgaard, J.; Dickens, C. F.; Chorkendorff, I.; NÃ¸rskov, J. K.; Jaramillo, T. F. Combining Theory and Experiment in Electrocatalysis: Insights into Materials Design. Science 2017, 355 (6321), eaad4998.
(4) Sanchez, J.; Ramos-GarcÃ©s, M. V.; Narkeviciute, I.; ColÃ³n, J. L.; Jaramillo, T. F. Transition Metal-Modified Zirconium Phosphate Electrocatalysts for the Oxygen Evolution Reaction. Catalysts 2017, 7 (12), 132.
(5) Strickler, A. L.; Escudero-Escribano, M.; Jaramillo, T. F. CoreâShell Au@Metal-Oxide Nanoparticle Electrocatalysts for Enhanced Oxygen Evolution. Nano Lett. 2017, 17 (10), 6040â6046.