Cited by 2.4kOpen Access
University of Minnesota
ORCID: 0000-0002-3431-8290Publishes on Electrocatalysts for Energy Conversion, Electronic and Structural Properties of Oxides, Electrochemical Analysis and Applications. 148 papers and 13.5k citations.
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The rational design of non-precious transition metal perovskite oxide catalysts holds exceptional promise for understanding and mastering the kinetics of oxygen electrocatalysis instrumental to artificial photosynthesis, solar fuels, fuel cells, electrolyzers, and metal–air batteries.
Perovskites such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF82) can be highly active for the oxygen evolution reaction (OER) upon water oxidation in alkaline solution. Here we report that BSCF82 can quickly undergo amorphization of its surface at OER potentials, which is accompanied by reduced surface concentrations of Ba2+ and Sr2+ ions as well as increased pseudocapacitive and OER currents. Such quick amorphization during OER was also observed for perovskite catalysts with similar OER activities such as Ba0.5Sr0.5Co0.4Fe0.6O3−δ and SrCo0.8Fe0.2O3−δ. In contrast, perovskite oxides with lower OER activities than BSCF82 did not undergo this transformation when subjected to identical electrochemical conditions. These findings demonstrate that the active chemistry and structure of oxide catalysts during OER can significantly differ from those of the as-synthesized material and that understanding how the oxide surface may change and impact the OER activity is critical to the design of highly active and stable OER catalysts.
This work experimentally identifies the charge-transfer energy as a key factor governing the catalytic oxygen evolution reaction (OER) activity and mechanism across a wide range of perovskite chemistries.
The activities of the oxygen evolution reaction (OER) on IrO2 and RuO2 catalysts are among the highest known to date. However, the intrinsic OER activities of surfaces with defined crystallographic orientations are not well-established experimentally. Here we report that the (100) surface of IrO2 and RuO2 is more active in alkaline environments (pH 13) than the most thermodynamically stable (110) surface. The OER activity was correlated with the density of coordinatively undersaturated metal sites of each crystallographic facet. The surface-orientation-dependent activities can guide the design of nanoscale catalysts with increased activity for electrolyzers, metal-air batteries, and photoelectrochemical water splitting applications.