We report the fabrication of membranes hundreds of micrometers thick that demonstrate efficient electron conduction and proton transport through vertically aligned arrays of multiwalled carbon nanotubes (NTs) impregnated by epoxy. Electrical transport was Ohmic with a conductivity of 495 mS cm(-1). Protons traversed the membrane through the NT bore with a current of 5.84 × 10(-6) A. Good electron and proton transport, chemical robustness, and simple fabrication suggest NT membranes have potential in artificial photosynthesis applications.

Here we discuss the photon-driven transport of protons and electrons over hundreds of microns through a membrane based on vertically aligned singlewalled carbon nanotubes (SWNTs). Electrons are photogenerated in colloidal CdSe quantum dots that have been noncovalently attached to the carbon nanotube membrane and can be delivered at potentials capable of reducing earth-abundant molecular catalysts that perform proton reduction. Proton transport is driven by the electron photocurrent and is shown to be faster through the SWNT-based membrane than through the commercial polymer Nafion. The potential utility of SWNT membranes for solar water splitting applications is demonstrated through their excellent proton and electron transport properties as well as their ability to interact with other components of water splitting systems, such as small-molecule electron acceptors.

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