Formation of hydrous gold(I) oxide in the process of self-assembled cysteine on gold nanoparticles and its electrocatalytic application

► We investigate electrochemical behavior at Au surface after self-assembled cysteine. ► The cyclic voltammogram shows a pair of well-shaped redox peaks. ► Hydrous gold(I) oxide is formed on the interfacial of the modified electrode. ► This oxide can participate in electrocatalytic processes as mediator.