| AVS 62nd International Symposium & Exhibition | |
| Thin Film | Wednesday Sessions |
| Session TF+EN-WeM |
| Session: | ALD for Energy |
| Presenter: | Adrie Mackus, Stanford University |
| Authors: | A.J. Mackus, Stanford University K.L. Pickrahn, Stanford University J.G. Baker, Stanford University S.F. Bent, Stanford University |
| Correspondent: | Click to Email |
The splitting of water to form hydrogen using sunlight as the source of energy has been actively researched in recent years to enable the production of green alternatives to fossil fuels. One of the main challenges in this technology is to develop a photoanode that (i) absorbs sunlight, (ii) has the ability to catalyze the oxygen evolution reaction (OER), (iii) is chemically stable in the aqueous electrolyte, and (iv) is made of earth-abundant materials. A strategy to synthesize an improved photoelectrochemical cell is to decouple these functions by conformally coating (e.g. by atomic layer deposition, ALD) a catalytic and protective layer on a nanostructured light-adsorbing material.1
In this work, we investigate ALD of NiO and NiFexOy films and their use as catalysts for the OER. The material NiFexOy was chosen because it is one of the most promising OER catalysts. The NiFexOy films were deposited using an ALD process that combines NiO ALD (NiCp2, O3) with Fe2O3 ALD (FeCp2, O3) in a supercycle. Alternatively, NiFexOy films were prepared by soaking ALD-grown NiO films in Fe-containing KOH electrolyte.2 Using the latter approach, the best results were obtained when the electrode was preconditioned in Fe-poor KOH, causing the smooth and compact NiO film to partly exfoliate, which increases the number of electrochemically accessible Ni sites. Synchrotron-radiation X-ray diffraction was employed to investigate the phase of the material as a function of the deposition conditions. Moreover, the catalytic activity of the films for the OER was investigated by cyclic voltammetry (CV). It was found that incorporating Fe in the NiO films enhances the activity for OER significantly with a 10-fold increase of the turnover frequency.
1. T.M. Gür, S.F. Bent, and F.B. Prinz, J. Phys. Chem. C118, 21301 (2014)
2. Y.T. Chong, E.M.Y. Yau, K. Nielsch, and J. Bachmann, Chem. Mater.22, 6506 (2010)