Modulating Electronic Structure by Etching Strategy to Construct NiSe 2 /Ni 0.85 Se Heterostructure for Urea-Assisted Hydrogen Evolution Reaction.

Exploring and developing novel strategies for constructing heterostructure electrocatalysts is still challenging for water electrolysis. Herein, a creative etching treatment strategy is adopted to construct NiSe 2 /Ni 0.85 Se heterostructure. The rich heterointerfaces between NiSe 2 and Ni 0.85 Se emerge strong electronic interaction, which easily induces the electron transfer from NiSe 2 to Ni 0.85 Se, and tunes the charge-state of NiSe 2 and Ni 0.85 Se. In the NiSe 2 /Ni 0.85 Se heterojunction nanomaterial, the higher charge-state Ni 0.85 Se is capable of affording partial electrons to combine with hydrogen protons, inducing the rapid formation of H 2 molecule. Accordingly, the lower charge-state NiSe 2 in the NiSe 2 /Ni 0.85 Se heterojunction nanomaterial is more easily oxidized into high valence state Ni 3+ during the oxygen evolution reaction (OER) process, which is beneficial to accelerate the mass/charge transfer and enhance the electrocatalytic activities towards OER. Theoretical calculations indicate that the heterointerfaces are conducive to modulating the electronic structure and optimizing the adsorption energy toward intermediate H * during the hydrogen evolution reaction (HER) process, leading to superior electrocatalytic activities. To expand the application of the NiSe 2 /Ni 0.85 Se-2h electrocatalyst, urea is served as the adjuvant to proceed with the energy-saving hydrogen production and pollutant degradation, and it is proven to be a brilliant strategy.