Three-dimensional carbon nanotube–polypyrrole–[NiFe] hydrogenase electrodes for the efficient electrocatalytic oxidation of H2

Hydrogenase electrodes for hydrogen oxidation are elaborated by an innovative immobilization strategy of [NiFe] hydrogenases from Desulfovibrio fructosovorans on highly porous single-walled (SWCNT) and multi-walled (MWCNT) carbon nanotube electrodes.The bioelectrode fabrication involved the adsorption of hydrogenase and amphiphilic pyrrole monomer functionalized by a methylviologen moiety on the nanotube deposits.The electropolymerization of the adsorbed monomer then leads to the enzyme entrapment in polypyrrole film surrounding the nanotubes. In addition, the redox polypyrrole achieves an efficient electrical wiring of hydrogenase on SWCNT and MWCNT electrodes via a mediated electron transfer. The latter configuration showed improved performances in catalytic responses (up to 0.30 ± 0.01 mA cm−2) at stationary electrodes due to the more appropriate wettability of MWCNTs. This led to a better coating of the nanostructured surface and thus, to an enhanced mediated electron transfer between the enzyme and the nanotubes.

► Electrical wiring of entrapped [NiFe] hydrogenases by viologen-polypyrrole films.
► Entrapment of hydrogenase within a polypyrrole film surrounding the nanotubes.
► Nanotube coatings markedly increase the electroenzymatic oxidation of hydrogen.
► Highly porous MWCNT deposits are more efficient than SWCNT for hydrogenase electrodes.