Material Discovery and Design Principles for Stable, High Activity Perovskite Cathodes for Solid Oxide Fuel Cells

Abstract

Critical to the development of improved solid oxide fuel cell (SOFC) technology are novel compounds with high oxygen reduction reaction (ORR) catalytic activity and robust stability under cathode operating conditions. We have screened approximately 2145 distinct perovskite compositions for potential use as high activity, stable SOFC cathodes, and have verified that our screening methodology qualitatively reproduces the experimental activity, stability, and conduction properties of well-studied cathode materials. We used the calculated oxygen p-band center as a first principles-based descriptor of the surface exchange coefficient (k*), which in turn correlates with cathode ORR activity. We used convex hull analysis under operating conditions in the presence of oxygen, hydrogen, and water vapor to determine thermodynamic stability. This search has yielded 52 potential cathode materials with good predicted stability in typical SOFC operating conditions and predicted k* on par with leading ORR perovskite catalysts. We also used our established trends in predicted k* and stability to suggest methods of improving the performance of known promising compounds. The materials design strategies and new materials discovered in our computational search will help enable the development of high activity, stable compounds for use in future solid oxide fuel cells and related applications.

Electronic, transport and optical properties in perovskite compound LaGaO3

“…In this one the A cation is situated at the corner of the cube, while B cation is situated at the centre. This variety of ABO 3 combinations give us materials that can be used in various fields such as photovoltaic [7], solid oxide fuel cells (SOFC) [8,9] and batteries [10,11]. The LaAlO 3 , a typical perovskite with variety applications, has allured considerable interest as over layer in conventional thermal barrier coatings [12], as a Promotion of electrochemical performances of LiNi 0 .…”

Activity‐Stability Volcano Plots for Material Optimization in Electrocatalysis

“…Volcano plots arise when two or even more competing processes determine the activity. In prototypical activity-based volcano plots, [7][8][9][10][11][12][13][14][15][16][17][18][19][20]60,61] the competing processes are reconciled with different elementary reaction steps of the reaction mechanism; for instance, the activity-based volcano curve for the CER over RuO 2 (110) corresponding to the traditional analysis at zero overpotential (cf. Figure 8) reveals an apex at ΔG 0 (O ot ) = (1.2 � 1.0) eV, corresponding to the intersection of the linear segments for the Volmer and the Heyrovsky step.…”

“…free energy diagram in Figure 2c). Beyond, the activity-stability approach facilitates to connect each elementary reaction step in its own overpotential regime with the stability as competing limiting quantity and enables to quantify the performance of electrode materials as function of the applied overpotential, quite in contrast to the prototypical activity-based volcano curve, [7][8][9][10][11][12][13][14][15][16][17][18][19][20]60,61] where the applied overpotential is not included into the analysis (cf. Figure 8).…”

“…Figure 8). Unlike the conventional activity-based volcano plot that consist of one apex only, [7][8][9][10][11][12][13][14][15][16][17][18][19][20]60,61] the activity-stability volcano approach reveals two apexes, in which the first apex, ΔG 0 (O ot ) = (1.86 � 0.47) eV, corresponds to optimum performance at η CER < 0.125 V, since the Heyrovsky step governs the underlying kinetics in the affiliated overpotential window (cf. Figure 2c).…”

“…[1] The underlying principle in conjunction with the volcano relation [2,3] results into activitybased volcano plots, a powerful tool in the field of heterogeneous catalysis, [4][5][6] electrocatalysis [7][8][9][10] or homogeneous catalysis [11] to comprehend on the activity of catalytic materials as function of a descriptor. In electrocatalysis, different descriptors such as the p-band center, [12,13] the free energy difference of an oxygen and a hydroxide adsorbate, [14] the free formation energy of adsorbed hydroxide, or the free formation energy of adsorbed oxygen are commonly applied depending on the underlying reaction; [15][16][17] in this context, the (free) formation energy of adsorbed oxygen has been shown to serve as suitable descriptor for the chlorine evolution reaction (CER) over transition metal oxides. [18][19][20] Due to significant advances in computing capacities, ab initio theory allows compiling volcano curves at low computational costs.…”