title: Applications of ALD MnO to electrochemical water splitting.
abstract: Atomic layer deposition (ALD) is an attractive method to deposit uniform catalytic films onto high surface area electrodes. One interesting material for ALD synthesis is MnOx, a promising earth-abundant catalyst for the oxygen evolution reaction (OER). It has previously been shown that catalysts beginning as MnO synthesized using ALD on smooth glassy carbon (s-GC) electrodes and Mn2O3 obtained upon annealing MnO on s-GC are active OER catalysts. Here, we use ALD to deposit MnO on high surface area GC (HSA-GC) substrates, forming an active catalyst on a geometric surface area basis. We then characterize three types of catalysts, HSA-GC MnO, s-GC MnO, and annealed MnO (Mn2O3), using cyclic voltammetry (CV), scanning electron microscopy (SEM), and ex situ X-ray absorption spectroscopy (XAS). We show that under OER conditions, all three catalysts oxidize to similar surface states with a mixture of Mn(3+)/Mn(4+) and that MnOx surface area effects can account for the observed differences in the catalytic activity. We also demonstrate the need for a high surface area support for high OER activity on a geometric basis.
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, CA 94305-5025, USA. sbent@stanford.edu.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Pickrahn
authors.forename: Yelena
authors.initials: Y
authors.lastname: Gorlin
authors.forename: Linsey C
authors.initials: LC
authors.lastname: Seitz
authors.forename: Aaron
authors.initials: A
authors.lastname: Garg
authors.forename: Dennis
authors.initials: D
authors.lastname: Nordlund
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Jaramillo
authors.forename: Stacey F
authors.initials: SF
authors.lastname: Bent