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

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 MoO 3 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 MoO 3 /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.