Rational design of N, C‐co‐doped Mo‒Mo ₂ C heterointerface nanofibers for pH‐universal electrocatalytic hydrogen evolution

Abstract The development of high‐efficiency, non‐precious metal electrocatalysts for the hydrogen evolution reactions (HERs) that operate robustly in both acidic and alkaline electrolytes is essential to replace costly Pt‐based catalysts. In this study, we present a novel heterostructure design: Mo‒Mo 2 C nanoparticles embedded within nitrogen and carbon co‐doped nanofibers (denoted as Mo‒Mo 2 C/NC NFs), fabricated via an organic‒inorganic hybridization strategy and subsequent hydrogen reduction. Our key material innovation lies in the precise regulation of the metallic Mo content, and thus the density of Mo‒Mo 2 C heterostructures, by controlling the aniline monomer dosage during synthesis. Comprehensive experimental characterization confirms that strong electronic coupling at these heterointerfaces effectively modulates the local electron density, leading to optimize hydrogen adsorption energy and enhanced H 2 desorption kinetics. Furthermore, the ternary conductive network, comprising metallic Mo, Mo 2 C nanoparticles, and N, C‐doped carbon, synergistically promotes charge transfer and inhibits nanoparticle agglomeration. As a result, the optimized electrocatalyst exhibits notable HER performance, achieving competitive overpotentials of 167 mV in 0.5 M H 2 SO 4 and 140 mV in 1 M KOH at 10 mA cm ‒2 , with Tafel slopes of 81 and 86 mV dec ‒1 , respectively. This work differentiates from prior Mo 2 C‐based systems by deliberate multi‐component interface engineering and presents a general strategy for designing high‐performance, pH‐universal electrocatalysts through precise heterostructure control.