A zinc-based metal organic framework and method of making is described. The zinc-based metal organic framework is in the form of an interpenetrating diamondoid framework where each Zn2+ ion center is linked with four other Zn2+ ion centers in a distorted tetrahedral geometry. The linking occurs through diamine and dicarboxylic acid linkers. The zinc-based metal organic framework may be deposited on a transparent conducting film and used as a photoelectrode for photoelectrochemical water splitting.