Extraordinary Hydrogen Evolution and Oxidation Reaction Activity from Carbon Nanotubes and Graphitic Carbons

The hydrogen evolution reaction, 2H<sup>+</sup> + 2<i>e</i><sup>–</sup> → H<sub>2</sub>, and its converse, the hydrogen oxidation reaction, H<sub>2</sub> → 2H<sup>+</sup> + 2<i>e</i><sup>–</sup>, are central to any realization of a hydrogen economy. Various forms of carbon have been used for decades as the precious metal catalyst support in these reactions. Here we report the unexpected result that single-wall carbon nanotubes and some graphitic carbons, activated by brief exposure to electrochemical potentials that induce hydrogen evolution in intercalating acids combined with extended soak times in such acids, acquire an activity for these reactions that exceeds that of known nonprecious metal catalysts.