Dihydrogen is prepared by the electrolysis of acidified of alkaline water using platinum electrodes. Generally, 15-20% of an acid `(H_(2)SO_(4))` or a base (NaOH) is used Reduction of water occurs at the cathode as:
`2OH^(-) to H_(2)O+(1)/(2)O_(2)+2e^(-)`
`therefore` Net reaction can be represented as:
`H_(2)O_(l) to H_(2_(s))+(1)/(2_(g))`
Electrical conductivity of pure water is ver low owing to the absence of ions in it. Therefore, electrolysis of pure water also takes at a low rate. If an electrolyte such as an acid or a base is added to the process, the rate of electrolysis increases. The addition of the electrolyte makes the ions available in the process for the conduction of electrolysis to take places.