Dynamic Surface Pre‐reconstruction and Selenization Co‐regulate the Electronic Structure of the Central Metal Ni and Promote the Efficient Water‐splitting

Abstract In the oxygen evolution reaction (OER), it is discovered that introducing defects into Ni‐based electrocatalysts can effectively enhance their catalytic activity. However, the specific structure of these defects and their role in modulating the performance of electrocatalysts remain unclear. Herein, an innovative core‐shell nano‐heterogeneous catalyst is reported that significantly boosts water decomposition efficiency through a strategy combining dynamic surface pre‐reconfiguration and selenization. The Ni₃Mo‐reconstruction@MoSe₂/NiSe₂ (NM‐Re@MS/NS) core‐shell heterogeneous catalyst is designed and synthesized. The surface pre‐reconstruction technique is employed to adjust the element distribution and induce the catalyst to form a more active surface phase. The MoSe₂/NiSe₂ (MS/NS) modulates the electronic structure and surface chemistry of the catalyst, thereby facilitating the adsorption/desorption of OH⁻ and *H. As anticipated, NM‐Re@MS/NS exhibited excellent catalytic activity for both the OER and hydrogen evolution reaction (HER) in 1.0 M KOH (OER: 258 mV@300 mA cm⁻²; HER: 65 mV@10 mA cm⁻²), with notable stability (OER: 80 h@250 mA cm⁻²; HER: 63h@250 mA cm⁻²). Importantly, in OER || HER system, the NM‐Re@MS/NS catalyst, acting as both cathode and anode, exhibits an overpotential of 284 mV at 300 mA cm⁻², significantly increasing the rates of hydrogen and oxygen production.