Preparation of porous Cu‐rich CuNi electrodes via electrochemically dealloying in ionic liquid

Commercial CuNi (55/45 wt%) alloy can be electrochemically dealloyed to be the porous Cu‐rich CuNi electrodes, which reveals an enhanced catalytic activity toward nitrate reduction in contrast with that of the mother alloy electrodes. In comparison with the use of aqueous electrolytes, the formation of the porous structures is reproducible if ionic liquid (IL) is used as the electrolyte for the dealloying process. During the dealloying process, a relatively more quantity of Ni but both Ni and Cu were electrochemically oxidized to be Ni(II) and Cu(II) complex ions; different ions seemed to own different coordinating molecules in accordance with the NMR analysis. Cu(II) ions could be reduced to Cu metal and deposited upon the counter electrode during the dealloying process. Ni(II) ions, on the other hand, can be mostly removed from the IL phase by extraction into the immiscible water phase. A sustainable system may be developed for the preparation of nitrate‐active electrodes in accordance with the study shown here. Commercial CuNi alloy can be easily converted to be Cu‐rich and porous CuNi electrode showing high activity toward electrochemical reduction of nitrate.