Enhancement of Electrocatalytic Activity for both Hydrogen and Oxygen Evolution Reactions of a Perovskite Oxide

Abstract

We have used both experimental and computational methods to show the significant impact of the incorporation of a 4d metal, Mo, into the perovskite oxide Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), which is known as a benchmark electrocatalyst for the anodic reaction of water-splitting. We demonstrate the enhanced electrocatalytic properties of the resulting catalytic material, Ba0.5Sr0.5Co0.5Mo0.5O3 (BaSrCoMoO6), where the presence of the 4d metal Mo leads to the formation of a double perovskite structure, as opposed to the simple perovskite structure of BSCF. The consequence of this transformation is the enhancement of the electrocatalytic properties of BaSrCoMoO6 over BSCF for both half reactions of water-splitting, i.e., hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Furthermore, BaSrCoMoO6 shows electrocatalytic activity for HER and OER in bulk form without additives, even carbon black, which is commonly added to HER and OER catalysts, including BSCF. Experiments for BaSrCoMoO6 with or without carbon black lead to similar overpotentials. Density functional theory (DFT) calculations reveal the effect of the structural transformation on the shift of the transition metal d bands toward the Fermi level, which correlates with the enhanced electrocatalytic activity.