Built‐in Electric Field Enhanced Water Splitting Kinetics via 3D MoS ₂ /NiSe ₂ /CC Nanoarray Heterostructure

The kinetics of gas evolution reactions are constrained by the dual limitations of interfacial mass transfer and charge transport, where hysteresis effects and charge accumulation at heterogeneous interfaces due to bubble adhesion constitute the key factors limiting efficiency. Interfacial engineering is employed to fabricate a three‐dimensional hierarchical MoS 2 /NiSe 2 /CC nanoarray heterostructure. Vertically aligned layered MoS 2 establishes directional channels for rapid bubble expulsion, while the oxyanions generated from its in situ oxidative dissolution electrostatically repel Cl − and protect the active sites. A significant work function difference between MoS 2 and NiSe 2 (ΔΦ = 0.36 eV) generates a strong built‐in electric field (BEF), which triggers interfacial electron rearrangement and boosts charge transfer efficiency, thereby enhancing bubble release via hydrophilicity/aerophobicity modification. Density functional theory simulations further reveal that this redistribution and the resulting down shift of the d‐band center collectively contribute to the enhanced catalytic kinetics. Consequently, the MoS 2 /NiSe 2 /CC demonstrates notable electrocatalytic performance, achieving a low oxygen evolution reaction overpotential of 240 mV at 10 mA cm −2 (140 mV lower than IrO 2 ) and exhibiting enhanced hydrogen evolution reaction activity that surpasses commercial Pt/C at current densities above 90 mA cm −2 . Such BEF construction strategy establishes a promising paradigm for optimizing gas evolution reaction kinetics.