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Open Access Publications from the University of California

Ultrathin Amorphous Silica Membrane Enhances Proton Transfer across Solid-to-Solid Interfaces of Stacked Metal Oxide Nanolayers while Blocking Oxygen

  • Author(s): Jo, WJ
  • Katsoukis, G
  • Frei, H
  • et al.

A large jump of proton transfer rates across solid-to-solid interfaces by inserting an ultrathin amorphous silica layer into stacked metal oxide nanolayers is discovered using electrochemical impedance spectroscopy and Fourier-transform infrared reflection absorption spectroscopy (FT-IRRAS). The triple stacked nanolayers of Co O , SiO , and TiO prepared by atomic layer deposition (ALD) enable a proton flux of 2400 ± 60 s nm (pH 4, room temperature), while a single TiO (5 nm) layer exhibits a threefold lower flux of 830 s nm . Based on FT-IRRAS measurements, this remarkable enhancement is proposed to originate from the sandwiched silica layer forming interfacial SiOTi and SiOCo linkages to TiO and Co O nanolayers, respectively, with the O bridges providing fast H hopping pathways across the solid-to-solid interfaces. Together with the complete O impermeability of a 2 nm ALD-grown SiO layer, the high flux for proton transport across multi-stack metal oxide layers opens up the integration of incompatible catalytic environments to form functional nanoscale assemblies such as artificial photosystems for CO reduction by H O. 3 4 2 2 2 2 3 4 2 2 2 2 −1 −2 −1 −2 +

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