One‐step controlled electrodeposition nickel sulfides heterointerfaces favoring the desorption of hydroxyl groups for efficient hydrogen generation

Abstract The heterointerface engineering involving different components or phases represents a desirable strategy for enhancing the sluggish kinetics of hydrogen evolution reaction (HER). However, constructing desired heterointerfaces and elucidating the reaction mechanisms on the interface remains a considerable challenge. In this work, we propose a straightforward electrochemical synthesis strategy to prepare the nickel sulfide‐based heterointerfaces for HER. The mechanism of electrochemical synthesis is revealed, wherein metal‐thiourea species can be formed at the cathode potential and subsequently oxidized to nickel sulfides at the anode potentials. Leveraging this mechanism, a range of nickel sulfides, including NiS, Ni 3 S 2 /NiS, Ni/Ni 3 S 2 and Ni 3 S 2 , have been successfully synthesized by tuning the potential range of cyclic voltammetry. Among these, the obtained Ni 3 S 2 /NiS@CC (CC: carbon cloth) exhibits the smallest overpotential of 84 mV at 10 mA·cm −2 and high stability. Theoretical calculations further reveal that the combination of NiS and Ni 3 S 2 induces electron redistribution at the interface, and thus the Volmer process is effectively promoted with faster water dissociation and OH desorption kinetics. Significantly, the simplicity method coupled with a clear synthesis mechanism and outstanding HER performance highlights its promising potential for practical applications.