Inheritable Organic‐Inorganic Hybrid Interfaces with π–d Electron Coupling for Robust Electrocatalytic Hydrogen Evolution at High‐Current‐Densities

Abstract Rational heterointerface engineering is crucial for superior and robust hydrogen evolution reaction (HER). Herein, a delicate organic‐inorganic hybrid heterojunction based on the assembly of oxalate with polyaniline (PANI) for HER at high‐current‐densities is envisioned. Strong π–d electron coupling is achieved between the delocalized π electrons of PANI and the localized d electrons of oxalate metal sites. The CoC₂O₄ nanosheets are grown on nickel foam (NF) with Ni²⁺ ions substitution by the precursor etching. By virtue of the synergy of hetero ions and π–d electron coupling, metal sites obtain sufficient exposure and electronic structure optimization. Surprisingly, the phase transition of oxalate during HER in the alkaline environment does not weaken the π–d electronic coupling of the organic‐inorganic hybrid interfaces. Inheritable interfacial electron interaction provides a reliable guarantee for robust stability at high‐current‐densities while endowing the hybrid materials with extremely low overpotentials. As expected, post‐phase reconstructed Co_0.59Ni_0.41(OH)₂@PANI/NF displays impressive HER activity, with a low overpotential of 43 mV@−10 mA cm⁻² and robust stability at −1000 mA cm⁻² for 30 h in the alkaline environment. This study sheds light on the rational heterostructure interface design and promotes the architecture of an impressive electrocatalysts system.