(509ar) Surface Proton Dynamics on BaZrO3: Implications for High Temperature Solid Electrolytes in Electrocatalysis
AIChE Annual Meeting
Wednesday, November 10, 2021 - 3:30pm to 5:00pm
Here, we use Density Functional Theory (DFT) calculations to rationalize proton conduction behavior in BaZr0.1Ce0.7Y0.1Yb0.1O3âÎ´ (BZCYYb). A common electrode in these systems is a composite material comprised of La0.7Sr0.3TiO3 (LST) and BZCYYb. We use BaZrO3 (BZO) to model the BZCYYb electrolyte and SrTiO3 (STO) to model LST for computational feasibility. We analyze the AO- and BO2-terminated (001) surfaces of both STO and BZO and consider existence of different transition metal (TM) catalysts on the surface. Kinetic barriers to hydrogen dissociation/recombination are presented on STO, BZO, and catalyst TMs on BZO and combined with the thermodynamic modeling of hydrogen incorporation into the BZO electrolyte bulk. We show that hydrogen recombination can occur directly on the BZO (001) surface without catalyst present, but that it is thermodynamically unfavorable for hydrogen gas to adsorb on the electrolyte. Thus, a catalyst is needed to dissociate hydrogen and inject the protons into the electrolyte, but that these protons are able to recombine and evolve into the gas phase directly from the electrolyte surface. Using these systems for electrochemical reactions that compete with HER will require more detailed electrolyte engineering to quench the parasitic HER.
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