Defect-Mediated Adsorption of Metal Ions for Constructing Ni Hydroxide/MoS₂ Heterostructures as High-Performance Water-Splitting Electrocatalysts

Electrochemical water splitting has attracted great attention as a promising technique for efficiently producing hydrogen with high purity. Developing noble metal-free electrocatalysts with good activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical for achieving economical water-splitting devices. In this work, we report a facile strategy to construct a Ni(OH)2/MoS2 heterostructure via defect-mediated metal ion adsorption. Abundant defects were introduced into MoS2 nanosheets using ion irradiation. By simply immersing the defective MoS2 nanosheets into a nickel acetate solution, Ni ions were adsorbed on the defect sites of MoS2 nanosheets and then transformed into a Ni hydroxide active phase. The obtained Ni(OH)2/irradiated MoS2 heterostructure exhibited both good HER and OER activities owing to the facilitated adsorption of reactants and reaction intermediates, as well as the strong electronic interactions near the heterointerfaces. The methodology used in this work can be generally applied to the synthesis of heterostructured electrocatalysts for other energy and environmental applications.