Boron leaching: Creating vacancy-rich Ni for enhanced hydrogen evolution

Creating vacancy is often highly effective in enhancing the hydrogen evolution performance of transition metal-based catalysts. Vacancy-rich Ni nanosheets have been fabricated via topochemical formation of two-dimentional (2D) Ni 2 B on graphene precursor followed by boron leaching. Anchored on graphene, a few atomic layered Ni 2 B nanosheets are first obtained by reduction and annealing. Large number of atomic vacancies are then generated in the Ni 2 B layer via leaching boron atoms. When used for hydrogen evolution reaction (HER), the vacancy-rich Ni/Ni(OH) 2 heterostructure nanosheets demonstrate remarkable performance with a low overpotential of 159 mV at a current density of 10 mA·cm −2 in alkaline solution, a dramatic improvement over 262 mV of its precursor. This enhancement is associated with the formation of vacancies which introduce more active sites for HER along Ni/Ni(OH) 2 heterointerfaces. This work offers a facile and universal route to introduce vacancies and improve catalytic activity.