The reactants in the industrial method of preparation of diborane are

Explanation

Electrolysis of 50% `H_2SO_4`, using high current density gives perdisulphuric acid
`2HSO_4^(-) (aq) overset("Electrolysis")(rarr)H_2S_2O_8 (aq) + 2e^(-)`
Hydrolysis of perdisulphuric acid gives hydrogen peroxide.
`H_2S_2O_8+2H_2O rarr 2H_2SO_4+H_2O_2`
2) Industrially it is prepared by the auto oxidation of 2 alkylanthraquinols.