The first try to use electrolysis in the formation of carbon structures was made by Namba in 1992, who precipitate the diamond-like carbon (DLC) films on silicon substrates using ethanol solutions at 70?C. The electrochemical process is dependent on numerous variables, including temperature, electrolyte, applied potential, current density, distance between electrodes, and the substrate for deposition61. The advantages comprises such as low cost, low temperature, scalability, endless possibilities for use of precursors, ability to use simple experimental equipment, and the flexibility to produce different structures. Methanol is one of the most used precursors and/or solvents in the reported electrochemical procedures, although DMSO, ethanol, acetonitrile, nitroethane and liquid ammonia were also applied; graphite were used as anodes; silica, nickel foil, SnO2-coated glass were used as substrates in the synthesis of DLC films62. There is a enormous variability in the voltage used; voltage can be set in the range between 2 and 5000 volts, which shows that these numerous variables can be changed in order to obtain the desired surface. Among other experimental reports, Roy et al.
formed DLC films by using a SnO2 substrate in an aqueous solution of acetic acid at room temperature and declare that the substrate had a deficiency in oxygen sites where molecules can be anchored, which promoted the breaking of chemical bonds and formation of species with sp2 and sp3 hybridizations63. DLC films and nano-inclusions of diamond, graphite, and lonsdaleite phase were synthesized from acetylene-saturated liquid ammonia at a temperature of -33? C by potentiodynamic, potentiostatic, galvanostatic, and pulsed deposition methods. The source of carbon was acetylene according to the reaction (1); electrolysis of these solutions resulted the conformation of deposition of a DLC film.
We emphasize that, this work carry the valuable tabulated information on the electrochemical synthesis of diamond thin films63,64.