A Zn93Cu7 electrocatalyst was prepared via electrodeposition. Previous reports have demonstrated that electrodeposition of metal precursors in acid solution can generate metal films (e.g. Cu, Ag, Pd, Zn and Sn) with highly porous surface caused by the formation of H2 bubbles during the process, known as dynamic hydrogen bubble template (DHBT) approach. Here we utilize the DHBT method to prepare a Zn-Cu alloy catalyst, where Zn 2+ and Cu 2+ precursors (Zn 2+ /Cu 2+ ratio = 60) in aqueous acidic solution were electrochemically reduced and deposited onto a Cu foil substrate to form an alloy film (see Supplementary Information). Scanning electron microscopy (SEM) of the Zn-Cu alloy (Figure , 2b) showed a uniform microporous morphology that is typically observed in metal films prepared by DHBT.