Electroanalytical chemistry with carbon film electrodes and micro and nano-structured carbon film-based electrodes

The recent development of electroanalysis using carbon film electrodes and micro and nano-structured carbon film based electrodes is reviewed. Graphite-like carbon film was synthesized by various methods such as thermal chemical vapor deposition and the thermolysis of organic polymers. Highly stable diamond film electrodes with a wide potential window have been synthesized by using the plasma CVD process and then employed for electroanalysis. A carbon film consisting of electron cyclotron resonance (ECR) sputter-deposited carbon films containing a large portion of sp(3) bonds was introduced. The film makes it possible to detect analytes with higher oxidation potential or electroactive species that foul the electrode Surface after oxidation. ECR carbon film can be deposited at low temperature and is conductive without doping. Graphite-like carbon films have been formed in order to construct various microelectrodes and microarray electrodes by using photolithography and dry etching methods to meet the requirements for improving the detection limit and for miniaturizing electrochemical detectors for small volume samples. For example, carbon film fabricated into an interdisfitated array (IDA) electrode has a very low detection limit for biochemicals such as catecholamines when used as an electrochemical detector for high-performance liquid chromatography (HPLC and capillary electrophoresis (CE). In contrast, composite carbon films containing various metal nanoparticles can be used for many analytes, including hydroGen peroxide and sugars. The films are deposited by the RF co-sputtering of metal and carbon. This is unlike other preparation methods such as the thermolysis of a polymer-metal complex or the electroplating of metal particles onto carbon film. The obtained carbon film contains 2-5 nm metal particles such as Pt, Ni, Cu, and In The highly sensitive and extremely stable detection of hydrogen peroxide, which is known to be the product of various oxidase enzymatic reactions, was achieved with sputter-deposited carbon film in which Pt nano-particles were dispersed. In contrast, carbon films containing dispersed Ni and Cu nanoparticles provide a high electrocatalytic current for sugars such as glucose and lactose in alkaline solution. By using the film as a detection electrode for HPLC, one can obtain a lower detection limit for several sugars than when using bulk metal electrodes.