Tuning of crystal phase of nickel telluride nanosheets to construct superior electrocatalyst for hydrogen evolution

It is of great significance to develop low cost, high-efficiency and environment-friendly electrocatalysts for hydrogen evolution reaction (HER) from water splitting. Herein, nickel telluride nanosheets grown on Ni Foam (NF) with three different crystal phases (NiTe, Ni2.6Te2 and Ni2.86Te2) are fabricated by one-step hydrothermal tellurization followed annealing process. The non-stoichiometric Ni2.86Te2/NF exhibits superior electrocatalytic HER performance compared to the NiTe/NF and Ni2.6Te2/NF, which is comparable to the state-of-the-art 20 wt% Pt/C catalyst at high current density. The Ni2.86Te2/NF only requires an overpotential of 348 mV to drive the current density of 200 mA cm−2 in a 1.0 M KOH electrolyte. Similarly, The Ni2.86Te2/NF delivered current densities of 200 mA cm−2 at the overpotential of 279 mV in 0.5 M H2SO4. Such excellent performance could be ascribed to the fast electron transfer and positive shift of dd-band center from its rich defective effect of crystal phase transition, as well as to the exposure of active sites provided by the two-dimensional nanosheets with large specific surface area. This work provides valuable insights for the rational modulation of the crystal phase on the nickel telluride for catalyzing HER.