(389g) Trends in Electrochemical Oxygen Reduction and Evolution Activities of Layered Double Hydroxides

Layered double hydroxides (LDH) have a general stoichiometry of A_xMO₂, where M is a first-row transition metal and A is an alkali intercalated metal or a proton. LDHs were originally discovered as battery electrode materials, but presently are also the most active oxygen evolution reaction (OER) catalysts in alkaline media ^[1]. However, their activities for OER and for oxygen reduction reaction (ORR) in full range of A_xand M stoichiometry is largely unexplored.

In this work, we perform a systematic high-throughput screening of A_xMO₂materials as bifunctional catalysts for OER and ORR using a simplified model. Our model is based on observation that the electro-catalytic activity to a large degree is defined by the surface coordination of the active site (M-atom) and is almost independent of the type of the A-atom or the layer-to-layer spacing. Using this model, we have found that our screening correctly detects the known active LDHs, but also identifies new very active OER and also ORR catalysts. The obtained systematic trends will also help to establish a principle to rationally design other materials as bifunctional catalysts for OER and ORR.

[1] S. Barwe, C. Andronescu, J. Masa, and W. Schuhmann, Current Opinion in Electrochemistry (2017).