Oxygen Evolution Reaction Activity of Sr₂Ta₂O₇ and Sr₂Nb₂O₇ Surfaces

Abstract

Oxide materials with a perovskite-derived layered structure often show better photocatalytic performance compared to nonlayered materials of similar composition. Here we investigate the catalytic activity for the oxygen evolution reaction (OER) on surfaces of the layered Carpy−Galy oxides Sr 2 Ta 2 O 7 and Sr 2 Nb 2 O 7 . We find that the (010) surface parallel to the layering shear plane is not relevant for photocatalysis. The (100) surface perpendicular to this plane, on the other hand, can catalyze the OER, at least for Sr 2 Ta 2 O 7 , whereas Sr 2 Nb 2 O 7 is inactive for the OER without a cocatalyst, both in agreement with experiment. The OER activity of Sr 2 Ta 2 O 7 ( 100) is, however, only retained while the surface does not assume a reconstructed stepped structure via Sr dissolution which we predict to be thermodynamically favored. Engineering Sr 2 Ta 2 O 7 into long-lasting photoelectrodes thus has to focus on exposing (100) facets as well as preventing Sr dissolution, for example, via a high Sr concentration in the electrolyte.

Comparative Study of Computational Hydrogen Electrodes and Constant Electrode Potential Models Applied to Electrochemical Reduction of CO2 and Oxygen Evolution Reaction on Metal Oxides/Copper Catalysts

“…We also studied and compared the results of OER on (FeO) 4 /Cu­(100), (CoO) 4 /Cu­(100), and (NiO) 4 /Cu­(100) using the CHE and CEP models at an applied potential of 1.23 V. The OER was considered to follow the mechanism described in the following equations: − …”

“…We also studied and compared the results of OER on (FeO) 4 /Cu(100), (CoO) 4 /Cu(100), and (NiO) 4 /Cu(100) using the CHE and CEP models at an applied potential of 1.23 V. The OER was considered to follow the mechanism described in the following equations: − + * H 2 O → OH * + false( normalH + + normale − false) : false( normalΔ G 1 false) OH * → O * + ( normalH + + normale − ) : 0.25em ( Δ G 2 ) O * + H 2 normalO → OOH * + ( normalH + + normale − ) : 0.25em ( Δ G 3 ) OOH * → O 2 ( …”

Crystal Structure Modification and Dielectric Properties of Sr- and La-Containing A2B2O7 Thin Films for High-Temperature Operational Film Capacitors

“…In contrast, as a material that does not contain Bi and has a Curie temperature in the high-temperature range, ferroelectrics having a layered perovskite structure with alternating layers of perovskite units and other layers in the long-axis direction of the crystal are other candidates. Ferroelectric materials with the layered perovskite structure, such as Sr 2 Nb 2 O 7 and Sr 2 Ta 2 O 7 , which have also been studied as photocatalytic materials, , show a high dielectric constant greater than 100 at both high and low temperatures. − However, because of the crystallographic direction dependence of the Curie–Weiss temperature, the temperature stabilities of the dielectric constant from room temperature to 300 °C for these thin films are unknown.…”