Controllable atom implantation for achieving Coulomb-force unbalance toward lattice distortion and vacancy construction for accelerated water splitting.

Engineering lattice strain, especially when it combines with the lattice distortion and vacancy (LDV) induced by locally unbalanced Coulomb forces (LUCFs), can improve the local coordination environment of atoms to achieve synergistically active sites and dynamic regulation of electrocatalysts, which are beneficial to high-performance bifunctional water splitting. Considering that Ni-based selenides possess abundant variable valence states, the Nb/Fe diatomic heterogeneous spin states are purposely introduced to produce LUCFs for improving the electronic coordination environment of the materials. The as-prepared Nb/Fe co-doped Ni-Ses (NbFe-NixSey) electrocatalyst exhibits the prominent oxygen and hydrogen evolution reaction (OER/HER) properties, with low overpotentials of 237 and 226 mV at 50 mA cm-2, respectively. The alkaline water electrolyzer with NbFe-NixSey as both anodic and cathodic electrodes only requires a cell potential of 1.7 V to reach 50 mA cm-2 in a continuous operation of 50 h. This work provides a new insight to regulate the electronic structure of advanced catalyst materials at the atomic level through LUCFs-induced LDV and further push forward the energy conversion technology.