Dense Crystalline‐Amorphous Nano‐Interfaces Derived from Local Reconstruction for Alkaline Hydrogen Evolution

The innovative proposed “dopant-dissolution-redeposition” mechanism triggers an intricate internal local amorphous transformation, endowing the reconstructed MoO₃/Mo-NiP with dense c-a nano-interfaces. As a result, the amorphous/crystalline MoO₃/Mo-NiP exhibits outstanding HER performance, achieving current density of 10 mA cm⁻² at ultra-low overpotentials of 26 mV with long-term stability in 1 m KOH.

Abstract

The crystalline-amorphous (c-a) interface can provide abundant accessible active sites and high intrinsic activity for hydrogen evolution reaction (HER); however, conventional methods only produce sparse c-a interface between hetero-phases. Here, a novel soluble dopant-induced local self-reconstruction strategy to yield dense c-a nano-interfaces is presented, as demonstrated by Mo doped-NiP pre-catalyst. During the cathodic polarization in alkaline electrolyte, the Mo dopant initially dissolves, generating abundant nano-voids within the NiP nanosheets; and subsequently forms in situ ultrafine amorphous MoO₃ nanoparticles, ranging from 2 to 4 nm in size, embedded in the crystalline NiP nanosheets. Compared with the conventional surface reconstruction that only generates sparse c-a interface, the proposed “dopant-dissolution-redeposition”, occurred in the surface and inner local regions around dopants, can yield dense c-a nano-interface. Theoretical calculations reveal that the c-a interface can efficiently modulate the electronic structure of interfacial sites and lower the HER overpotential. Benefiting from the dense c-a nano-interface, the amorphous/crystalline MoO₃/Mo-NiP exhibits outstanding HER performance, achieving current density of 10 mA cm⁻² at ultra-low overpotentials of 26 mV with long-term stability in 1 M KOH. This work provides a basis for tuning the composition-structure-property relationships of materials from both surface and interior.