A concept for immobilizing catalytic complexes on electrodes: cubic phase layers for carbon dioxide sensing.

Liquid crystalline cubic phases formed with monoolein and Myverol have been used as matrixes to host a catalytic complex of nickel(II) and 1-hexadecyl-1,4,8,11-tetraazacyclotetradecane for the reduction of carbon dioxide. The structures of the cubic phases, both with and without the catalyst, were established using small-angle X-ray scattering. The catalytic reduction of carbon dioxide was performed using thin mercury film and glassy carbon electrodes modified with cubic phases containing the catalyst. The linear dependence of the catalytic reduction current on the carbon dioxide concentration allowed use of the modified electrodes as sensing devices both in solution and in the gas phase. The high reproducibility of the measurements makes this method of monitoring carbon dioxide levels attractive compared to other methods based on modified electrodes.