Title: Nanoscale Limitations in Metal Oxide Electrocatalysts for Oxygen Evolution

Abstract

Metal oxides are attractive candidates for low cost, earth-abundant electrocatalysts. However, owing to their insulating nature, their widespread application has been limited. Nanostructuring allows the use of insulating materials by enabling tunneling as a possible charge transport mechanism. We demonstrate this using TiO₂ as a model system identifying a critical thickness, based on theoretical analysis, of about ~4 nm for tunneling at a current density of ~1 mA/cm². This is corroborated by electrochemical measurements on conformal thin films synthesized using atomic layer deposition (ALD) identifying a similar critical thickness. We generalize the theoretical analysis deriving a relation between the critical thickness and the location of valence band maximum relative to the limiting potential of the electrochemical surface process. The critical thickness sets the optimum size of the nanoparticle oxide electrocatalyst and this provides an important nanostructuring requirement for metal oxide electrocatalyst design.

Authors:

Viswanathan, Venkatasubramanian ^[1]; Pickrahn, Katie L. ^[2]; Luntz, Alan C. ^[3]; Bent, Stacey F. ^[2]; Nørskov, Jens K. ^[4]

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+ Show Author Affiliations

1. Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, United States, SUNCAT, SLAC National Accelerator Laboratory, Menlo Park, California 94025-7015, United States, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
2. Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, United States
3. SUNCAT, SLAC National Accelerator Laboratory, Menlo Park, California 94025-7015, United States
4. Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025, United States, SUNCAT, SLAC National Accelerator Laboratory, Menlo Park, California 94025-7015, United States

Publication Date:

Thu Sep 18 00:00:00 EDT 2014

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center on Nanostructuring for Efficient Energy Conversion (CNEEC)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1233977

Alternate Identifier(s):

OSTI ID: 1168333

Grant/Contract Number:  

SC0001060

Resource Type:

Published Article

Journal Name:

Nano Letters

Additional Journal Information:

Journal Name: Nano Letters Journal Volume: 14 Journal Issue: 10; Journal ID: ISSN 1530-6984

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (heterogeneous); solar (fuels); photosynthesis (natural and artificial); bio-inspired; electrodes - solar; defects; charge transport; materials and chemistry by design; synthesis (novel materials); nanostructuring; atomic layer deposition; water splitting