[Paper] Active MnOx Electrocatalysts Prepared by Atomic Layer Deposition for the Oxygen Evolution and Oxygen Reduction Reactions




Active MnOx Electrocatalysts Prepared by Atomic Layer Deposition for the Oxygen Evolution and Oxygen Reduction Reactions, Katie L. Pickrahn,Sang Wook Park, Yelena Gorlin, Han-Bo-Ram Lee, Thomas F. Jaramillo, and Stacey F. Bent, Advanced Energy Materials, 2012


http://dx.doi.org/10.1002/aenm.201200230


Abstract


The ability to deposit conformal catalytic thin fi lms enables opportuni- ties to achieve complex nanostructured designs for catalysis. Atomic layer deposition (ALD) is capable of creating conformal thin fi lms over complex substrates. Here, ALD-MnO x on glassy carbon is investigated as a catalyst for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), two reactions that are of growing interest due to their many applica- tions in alternative energy technologies. The fi lms are characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, ellipsometry, and cyclic voltammetry. The as-deposited fi lms consist of Mn(II) O, which is shown to be a poor catalyst for the ORR, but highly active for the OER. By controllably annealing the samples, Mn 2 O 3 catalysts with good activity for both the ORR and OER are synthesized. Hypotheses are presented to explain the large difference in the activity between the MnO and Mn 2 O 3 catalysts for the ORR, but similar activity for the OER, including the effects of surface oxidation under experimental conditions. These catalysts synthesized though ALD compare favorably to the best MnO x catalysts in the literature, demonstrating a viable way to produce highly active, conformal thin fi lms from earth-abundant materials for the ORR and the OER.