Nanoframes of Co3O4–Mo2N Heterointerfaces Enable High‐Performance Bifunctionality toward Both Electrocatalytic HER and OER

Abstract Interfacial engineering of heterostructured catalysts has attracted great interest in enabling both hydrogen and oxygen evolution reactions (HER and OER), by fine tuning of the interfacial geometry and electronic structures. However, they are not well structured for high‐performing bifunctionalities, largely due to the confined single particle morphologies, where the exposed surfaces and interfaces are limited. Herein, a hollow nanoframing strategy is purposely devised for interconnected Co 3 O 4 –Mo 2 N heterostructures that are designed with interfacial charge transfer from Mo 2 N to Co 3 O 4 , as rationalized by theoretical calculations and confirmed by X‐ray photoelectron spectroscopy analyses. It is shown that by the controllable pyrolysis of bimetallic Mo–Co Prussian blue analogue nanoframes (NFs) with an optimal Mo/Co ratio, the desired nanoframes of Co 3 O 4 –Mo 2 N heterostructure are successfully formed. The as‐synthesized Co 3 O 4 –Mo 2 N NFs not only inherit the functionalities of individual components and the electrolyte‐accessible nanoframe structure, and they also give an ideal heterointerface with strong electron interaction and favorable H 2 O/H* adsorption energies, leading to a remarkable enhancement in bifunctional catalytic activities (i.e., 12.9‐fold and 20‐fold higher current density under the 300 mV overpotential, as compared to the single‐phased Co 3 O 4 NFs alone toward HER and OER, respectively), while remaining a robust stability.