Received: September 19, 2007

In Final Form: December 5, 2007

Abstract:

In contrast to still inefficient and expensive technical proton-conducting membranes, which rely on sulfonic acid activity, biology has solved its energy-related proton-conduction problems by evolving protein-bordered channels exposing amino acids for proton conduction (bacteriorhodopsin, CF0-channel of ATP-synthase, cytochrome oxidase complex). In this contribution, amino acids (L-lysine, aspartic acid, methionin) were attached to silica nanoparticles, which were incorporated into narrow (100-400 nm) channels produced in proton-inactive membranes (polyethlyene terephthalate, polycarbonate) forming nanowire structures for protons. The amino acid-modified porous membranes were shown to function in a real fuel cell setup with energy conversion efficiencies, corrected for the pore densities, approaching those of state-of-the-art fuel cell membranes. The dependence of proton-conduction properties of these channels on different parameters was studied. Further development of proton-conduction channels lined or filled with amino acid-grafted nanoparticles will not only give access to the wealth of amino acid chemistry for further optimization, but proton-conduction channels may also work as basic elements in hierarchic structures linking proton currents with chemical catalysis or mechanical work.

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