Surface reconstruction of heterostructures in alkaline medium towards enhanced electrocatalytic hydrogen evolution

Constructing heterostructures has proved to be a successful strategy to fabricate electrocatalysts with high efficiency for water splitting. However, the structure evolution in alkaline hydrogen evolution reaction lacks investigation and the specific active center remains disputable. Herein, we take the well-designed Ni3S2@VO2 heterostructures as a model to investigate the electrocatalytic activity and the surface reconstruction process of heterostructure catalysts in alkaline electrolyte. The Ni3S2@VO2 heterostructures, with Ni3S2 nanorods as the core and VO2 nanoflakes as the shell, coupled with the high conductive Ni3S2, the hydrophilic VO2 and modulated electronic structures at the interfaces, exhibited prominent activity and superior stability at various current densities. Further, the ex-situ characterizations confirmed that the surface reconstruction from Ni3S2@VO2 into Ni3S2@amorphous-Ni(OH)(2) in alkaline media could optimize the water dissociation barrier and exposed large active area, thereby contributing to improved electrocatalytic performance. Our study not only introduces novel high-performance electrocatalysts for hydrogen evolution reaction (HER), but also provides a new avenue for re-examining hetero-structural catalysts in alkaline solutions.