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• The pure CuOOH series (C2/m, Pmn21 and Cmc21) are inert for OER/ORR. • Co and Rh can effectively activate CuOOH series as bifunctional OER/ORR electrocatalysts. • The 2D-L C2/m-CuOOH substrate decorated by Co and Rh only has η OER / ORR of 0.25 eV/0.22 eV and 0.36 eV/0.46 eV, respectively. Copper oxyhydroxide (CuOOH), an unavoidable oxidic product of CuO and Cu(OH) 2 electrocatalysts, is always ignored in water splitting. In this work, we investigated the OER /ORR electrocatalytic activity of all CuOOH series (C2/m, Cmc2 1, and Pmn2 1) and proposed an improvement scheme for catalytic activity using the DFT method. The results showed that pure CuOOH matrixes with large OER/ORR overpotentials (η OER / ORR) were inert toward OER/ORR. Therefore, eleven metals (Mn, Fe, Co, Ni, Zn, Mo, Ru, Rh, Pd, W, and Ir) were used to activate the CuOOH substrates. It is found that the OER/ORR performances of all CuOOH series can be significantly improved by Co or Rh doping. Especially for 2D-layered C2/m-CuOOH substrate, the η OER / ORR was reduced from 1.26 V/2.01 V to 0.25 V/0.22 V and 0.36 V/0.46 V by Co and Rh embedding, respectively, which mainly owes to the regulation from the moderate d-orbital electrons of doped Co and Rh. This work systematically revealed the OER/ORR performance of the CuOOH series, which will promote the development of new catalysts and help us to deeply understand and improve the OER/ORR performance of previous copper oxide electrocatalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • 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. [ABSTRACT FROM AUTHOR]