Ultrarapid synthesis Ni-Cu bifunctional electrocatalyst by self-etching electrodeposition for high-performance water splitting reaction

• Cu-doped Ni catalysts can be successfully synthesized by electrodeposition. • The incorporation of Cu can improve the electrocatalytic performance of Ni. • Cu-doped Ni can optimize the hydrogen binding energy on catalyst surface. Bifunctional catalyst, as a feasible way to produce hydrogen, has been regarded as an effective issue for mitigation of the greenhouse effect, and thus has attracted extensive attention. Inspired by the traditional electrodeposition technology, we report a fast self-etching electrodeposition method to construct copper-incorporated three-dimensional Ni-Cu coated on copper sheets as a superior bifunctional catalyst. During the electrodeposition process, the copper substrate was corroded to form ammonium copper ions by ingenious design of the concentration of electrolyte, including ammonium chloride and sodium chloride. Meanwhile, we observe that the ratio of Ni to Cu could be changed via varying the current density. The optimized hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials are 76 mV and 290 mV at 10 mA cm −2 , respectively, which outperform the most reported bifunctional electrocatalysts until now. The calculation further demonstrates that the theoretical hydrogen desorption energy and OER overpotential of Ni-Cu are better than those of pure Ni and Cu. The prepared Ni-Cu electrocatalyst exhibits remarkable stability, especially in the HER reaction process stability test up to 50 h. The successful preparation of Ni-Cu electrocatalyst provides more possibility in the traditional electrodeposition synthesis of high performance electrocatalysts.