Oxygen Evolution Reaction on Perovskites: A Multieffect Descriptor Study Combining Experimental and Theoretical Methods

Abstract

The correlation between ex situ electronic conductivity, oxygen vacancy content, flat-band potential (Efb), and the oxygen evolution reaction (OER) activity for a wide range of perovskite compositions [La1-xSrxCoO3−δ series (with x = 0, 0.2, 0.4, 0.6, 0.8), LaMO3−δ series (M = Cr, Mn, Fe, Co, Ni), Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), and PrBaCo2O6−δ (PBCO)] are investigated experimentally and theoretically. It is found that all of these parameters can affect the OER activity; however, none of them alone play a crucial role in determining the electrocatalytic activity. The correlation of one single physicochemical property with the OER activity always presents deviation points, indicating that a limitation does exist for such 2-dimensional correlations. Nevertheless, these deviations can be explained considering other physicochemical properties and their correlation with the OER activity. Hence, this work aims in simultaneously linking the OER activity with several physicochemical materials properties. The concept of the OER/multidescriptor relationship represents a significant advancement in the search and design of highly active oxygen evolution catalysts, in the quest for efficient anodes in water electrolyzers.

Polar or not polar? The interplay between reconstruction, Sr enrichment, and reduction at the La0.75Sr0.25MnO3 (001) surface

“…Together with an energy cutoff of 550 eV this approach ensures convergence of total energies and bulk vacancy formation energies within 4 meV/atom. To reliably study surface segregation we model the LSM25(001) surface in a symmetric slab with [15][16][17][18][19] layers, corresponding to 7.5-9.5 ABO 3 bilayers. Surface free energies (cf.…”

Fe-Doping in Double Perovskite PrBaCo2(1-x)Fe2xO6-δ: Insights into Structural and Electronic Effects to Enhance Oxygen Evolution Catalyst Stability

“…Based on above evidence, the addition of Fe seems to aid Co to be stable in a lower oxidation state by providing charge stabilization through balancing oxygen non-stoichiometry, and therefore promotes formation of oxygen vacancies. In the presence of higher oxygen vacancy concentration, the lattice oxygen within the perovskite structure is more inclined to participate in the water oxidation reaction (i.e., LOER) and develops the OER active oxy(hydroxide) layer at the surface [3,27]. Figure 5a shows a shift of the Co K-edge XANES spectra to higher energy positions of PBC, PBCF82, and PBCF55 during the operando flow cell test, among which PBCF55 reveals the greatest extent of energy shift of ~0.7 eV at the highest potential, while PBC and PBCF82 display ~0.3 eV of edge shifts.…”

“…Therefore, an efficient oxygen evolution reaction (OER) is essential since it is the key reaction in water electrolysis. During the past decade, the members of the perovskite oxide family (ABO 3 ) have been gaining vast attention for their promising activities as OER electrocatalysts under alkaline conditions, and thereby relieving the need of expensive precious metals such as iridium [2][3][4][5][6][7]. Generally, perovskite oxides are composed of rare-earth (e.g., lanthanides) or earth alkaline metals (e.g., Ba) in the A-site and 3D transition metals in the B-site (e.g., Ni, Co and/or Fe).…”

“…This substitution can transpire in both A-and B-sites of the perovskite (i.e., A' 1-n A" n B' 1-m B" m O 3 ; 0 ≤ n, m ≤ 1) either in ordered or random arrangement [10]. Likewise, cation ordering plays an important role in engineering the intrinsic properties of a perovskite such as electronic structure, ionic conductivity, and magnetic properties, all of which may change its electrocatalytic behavior [3,10,11]. The recently proposed OER mechanism emphasizes that the formation of oxy(hydroxide) layer at metal oxide surface is essential along the path of lattice oxygen evolution reaction (LOER) [12,13].…”

Rationality in the new oxygen evolution catalyst development

“…[62,63] Complex descriptors combining the conductivity, oxygen vacancy content, and flat band potential represent the most recent approach in OER descriptor design. [64] It needs to be stressed that the listed examples usually address only catalysts conforming to a single structural type and finding experiment based effective descriptor for structurally different OER catalysts remains challenging. Surprisingly, the local structure of the OER active transition metal cations seems to be underrepresented among the intended OER descriptors compared to those based on band structure.…”