Electrocatalysts for the oxygen evolution reaction (OER) play an important role in many developing energy technologies, lowering the needed overpotential and providing electrons to important synthesis reactions including the production of hydrogen or ammonia and the reduction of CO2 to form fuels.  Metal oxides are attractive OER catalysts, but charge transport limitations may mask the intrinsic activity of the surface.  Thin films are an excellent test bed for these materials, and atomic layer deposition (ALD) is an attractive method to deposit uniform thin films with a fine control over film thickness. In this presentation, we explore ternary oxide electrocatalysts deposited by ALD.  Mixtures of Mn and Ti oxides are deposited by ALD using bis(ethylcyclopentadienyl) manganese, titanium isoproxide, and water as reactants.  Shifts in the Ti-2p3/2 and Mn-2p3/2 binding energies are seen with mixing, indicating well-dispersed catalysts.  The activity over the span of compositions was characterized for films with thicknesses under 2.8 nm.  We find that the activity is correlated with composition, and that activity increases monotonically with increasing Mn concentration.  At concentrations between ~10 to ~60 % Mn, a suppression in the activity of individual Mn active sites is observed, consistent with theoretical predictions. The importance of thin films is also explored.  The activity is seen to rapidly decay at thicknesses greater than ~5 nm for 66% Mn films, and ~10 nm for 95% Mn films.  These results are compared with other ALD-deposited OER electrocatalysts that we have explored including MnO and NiO.  We believe this is the first study of ternary oxide OER electrocatalysts deposited by ALD.  The results show that ALD is a useful method for growing compositionally-controlled, ultrathin ternary oxide catalysts.

Atomic layer deposition of ternary oxide electrocatalysts for water splitting

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.