2023 Volume 2 Issue 3 Pages 130-145
Applying a carbon coating to a non-conductive nanoporous ceramic makes it possible to use it as a conductive electrode while maintaining its shape. In the case of mesoporous silica (MPS), the silica surface can be completely covered with one or two layers of graphene by CVD using the catalytic effect of Si radicals. Similarly, nitrogen-doped carbon can be applied using a nitrogen-containing organic gas as the carbon source. Analysis of the effects of nitrogen doping using water-based capacitor measurements with carbon-coated MPSs (C-MPS) shows that the pseudocapacitance increase caused by doping corresponds to the number of pyridine-derived nitrogen atoms in the carbon film. A carbon-coated anodic aluminum oxide (C-AAO) film has aligned nanopores between the front and back surfaces, which provide a very good diffusion path for other materials. We have developed an electrode in which redox enzymes are immobilized in an orientation favorable to the electrocatalytic reaction by utilizing the electrostatic interaction between the enzyme and the C-AAO film. In the case of a biocathode with laccase immobilized on a C-AAO film, the reaction efficiency of the electrode prepared by controlling the enzyme orientation by applying a voltage of +0.65 V to the C-AAO film in the pH 5.0 solution was 1.5 times that of an electrode prepared using only physical adsorption.
