Trends of epitaxial perovskite oxide films catalyzing the oxygen evolution reaction in alkaline media

Abstract

The oxygen evolution reaction (OER) is considered a key reaction for electrochemical energy conversion but slow kinetics hamper application in electrolyzers, metal-air batteries and other applications that rely on sustainable protons from water oxidation. In this review, the prospect of epitaxial perovskite oxides for the OER at room temperature in alkaline media is reviewed with respect to fundamental insight into systematic trends of the activity. First, we thoroughly define the perovskite structure and its parameter space. Then, the synthesis methods used to make electrocatalytic epitaxial perovskite oxide are surveyed and we classify the different kinds of electrodes that can be assembled for electrocatalytic investigations. We briefly discuss the semiconductor physics of epitaxial perovskite electrodes and their consequences for the interpretation of catalytic results. OER investigations on epitaxial perovskite oxides are comprehensively surveyed and selected trends are graphically highlighted. The review concludes with a short perspective on opportunities for future electrocatalytic research on epitaxial perovskite oxide systems.

Carbonate formation lowers the electrocatalytic activity of perovskite oxides for water electrolysis

“…[2][3][4][5][6][7] Due to the complexity of the active surface under operation conditions, further optimization of catalyst activity and stability makes use of single crystalline catalyst surfaces to derive structure-function relationships between the reactivity and the atomic-level surface structure and composition. [8][9][10] Epitaxial thin lms allow investigation of oxide catalysts fabricated with unit-cell precision. 11 Recently, we used epitaxial LaNiO 3 layers to demonstrate the important role of the surface terminating layer composition, 12 an activity descriptor that is difficult to recognize in catalysts fabricated using traditional routes.…”

Contribution of the Sub‐Surface to Electrocatalytic Activity in Atomically Precise La0.7Sr0.3MnO3 Heterostructures

“…The density of active sites is often simply approximated by the exposed geometric surface area (measured by, e.g., microscopy or N 2 adsorption [16] ) or the electrochemical surface area (ECSA) by assumptions regarding intrinsic capacitance. [15,[17][18][19] However, all of these normalization approaches imply that electrochemical activity is governed exclusively by the terminal surface layer of the oxide, without serious consideration of sub-surface layers that may influence activity as well.Size effects in the OER activity of nanoparticles, [20,21] thickness-dependent effects in thin films, [22] and substrate-dependent effects in 2D materials [23] imply that while a catalytic reaction occurs at the catalyst/electrolyte interface, the supporting layers of a catalyst (and/or its support) can influence activity as well. For oxides, these size effects can include manipulating the ability of transition metal sites to oxidize prior to the onset of OER.…”

Recent Progress in the Development of Screening Methods to Identify Electrode Materials for the Oxygen Evolution Reaction

“…Further activity descriptors for perovskites in the OER aside the frameworks of the e g occupancy and the O p‐band center are discussed in the works of Hong et al. or Antipin and Risch, [ 67,73 ] but are not further addressed in this progress report.…”

“…Sections 2.1-2.4), the activity descriptors discussed in this section are not universally applicable to arbitrary classes of OER materials. Further activity descriptors for perovskites in the OER aside the frameworks of the e g occupancy and the O p-band center are discussed in the works of Hong et al or Antipin and Risch, [67,73] but are not further addressed in this progress report.…”

“…The O p-band center has been successfully applied as activity descriptor to identify perovskite-based materials for the OER and ORR, [66][67][68][69][70][71][72][73] and its application has also shown to be suitable to address activity trends of spinel oxides (AB 2 O 4 ) in the OER. [74,75] However, also critical remarks should be noted, referring to the work of Yamada et al, who reported that the O p-band center as descriptor is not necessarily appropriate for a large amount of perovskites.…”