Valence configurations of active sites are essential for modulating the electronic structure of the non-noble metal electrocatalysts in water splitting. However, synchronously engineering the valence states of different elements to inverse ones has been a key challenge in the integrated synthesis environment. Herein, for the first time, a novel superstructure of inverse spinel NiCoFe oxide nanocubes with contemporaneous valence regulation to preferred Co²⁺ and Ni³⁺ (Ni^IIICo^IIFe-O@NF, NF stands for nickel foam), has been developed by in situ topotactic chemical transformation. Ni^IIICo^IIFe-O@NF can attain a current density of 10 mA cm⁻² at a low cell voltage of 1.455 V in 1 M KOH when used as bifunctional catalysts. Density functional theory calculations suggested that the favorable Co²⁺ and Ni³⁺ act synergistically to lower down ΔG_H* for HER and the OER overpotential in an optimal pathway. Our study probes the construction and understanding of the heterogeneous valence configuration in a single phase.

活性位的价构型对于水分解中调节非贵金属电催化剂的电子结构至关重要。然而，在集成综合环境中，将不同元素的价态同步工程化为相反的价态已成为关键挑战。在此，首次开发了一种新型尖晶石逆向尖晶石型NiCoFe氧化物纳米立方体，该结构具有对优选Co ²⁺和Ni ^3+的同时价数调节（Ni ^III Co ^II Fe-O @ NF，NF代表泡沫镍）。通过原位化学转化。Ni ^III Co ^II Fe-O @ NF的电流密度可以达到10 mA cm ^-2用作双功能催化剂时，在1 M KOH中在1.455 V的低电池电压下保持稳定。密度泛函理论计算表明，有利的Co ²⁺和Ni ³⁺协同作用，以最佳途径降低HER和OER过电势的ΔGH _*。我们的研究探讨了单价异构构型的构建和理解。