Co‐Constructing Interfaces of Multiheterostructure on MXene (Ti 3 C 2 T x )‐Modified 3D Self‐Supporting Electrode for Ultraefficient Electrocatalytic HER in Alkaline Media

Electrocatalysis is a potential method for sustainable hydrogen production, and the development of non‐noble metal‐based effective electrocatalysts for electrochemical water splitting is the core of exploiting and utilizing renewable energy. Herein, a stupendous electrocatalyst with multiheterostructure interfaces and 3D porous structure is synthesized, and the mechanisms of enhanced electrocatalytic activity combining multicharacterizations and density functional calculations are clarified. Especially, the fabricated Co 2 P/N@Ti 3 C 2 T x @NF (denoted as CPN@TC) exhibits an ultralow overpotential of 15 mV to arrive at a current density of 10 mA cm −2 with the long‐term durability and a small Tafel slope of 30 mV dec −1 in 1 m KOH, which even compares with noble metal catalysts favorably. The outstanding HER activity is ascribed to multiheterointerfaces for adsorbing H 2 O and H*, fine conductivity for the electronic transmission, and well‐designed structure for rapid transport of ions and gases. It is reasonable to think that the synthetic strategy of CPN@TC can be extended to the preparation of transition‐metal‐based phosphides for enhanced catalytic performance.