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The development of highly efficient and low-cost bifunctional noble metal-free electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is an effective strategy for improving efficiency. Herein, novel three-dimensional (3D) bimetallic metal–organic frameworks containing Ni and V with adjustable stoichiometry were synthesized on nickel foam successfully. Notably, Ni2V-MOFs@NF only require rather low overpotentials of 244 and 89 mV for the OER and HER, respectively, and expedites overall water splitting with 1.55 V at 10 mA cm–2 with robust durability during the 80 h test. The high efficiency of the novel obtained electrocatalysts should be attributed to the particular morphological design of the two-dimensional (2D) ultrathin nanosheets self-assembling into a 3D nanoflower and the electronic structure regulation resulting from the synergetic interaction between nickel and vanadium. Subsequent theoretical calculations reveal the following conclusions: (I) the exceptional electronic conductivity of Ni2V-MOFs shows enhanced optimization as a result of electronic structure reconstruction, (II) the energy barrier reduction of the rate-limiting step is responsible for the enhanced dynamics of Ni2V-MOFs for the OER, and (III) the facilitation of the adsorption of H+ and H2O plays a key role in progressing the HER catalytic activity of Ni2V-MOFs.

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The research and development of transition metal oxides based electrocatalysts with high activity and stability for both oxygen evolution reaction and hydrogen evolution reaction via a facile design strategy is of critical importance. Herein, we fulfill both significant oxygen evolution reaction and hydrogen evolution reaction improvement in activity by hierarchically nanostructured Ce-MnCo 2 O 4 prepared by an oxalate coprecipitation method and a followed calcination process. X-ray photoelectron spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy mappings analysis show that the hierarchically nanostructured Ce-MnCo 2 O 4 -3% sample is homogeneously modified by 1.49 wt % Ce with increased Co 3+ species. We suspect that the introduction of suitable Ce content into MnCo 2 O 4 facilitates the oxygen transfer and the formation of Co 3+ species, and modifies the local chemical binding, resulting in active performance for oxygen evolution reaction (390 mV at 10 mA•cm −2 and a Tafel slope of 125 mV•dec −1 ) in 1.0 M KOH solution. In addition, the Ce-MnCo 2 O 4 -3% sample also exhibits hydrogen evolution activity with overpotential of 389 mV at 10 mA•cm −2 and a Tafel slope of 96 mV• dec −1 , and relatively good long-time stability for 12 h.