NiTe2 Nanowire Outperforms Pt/C in High-Rate Hydrogen Evolution at Extreme pH Conditions.

Better hydrogen generation with nonprecious electrocatalysts over Pt is highly anticipated in water splitting. Such an outperforming nonprecious electrocatalyst, nickel telluride (NiTe2), has been fabricated on Ni foam for electrocatalytic hydrogen evolution in extreme pH conditions, viz., 0 and 14. The morphological outcome of the fabricated NiTe2 was directed by the choice of the Te precursor. Nanoflakes (NFs) were obtained when NaHTe was used, and nanowires (NWs) were obtained when Te metal powder with hydrazine hydrate was used. Both NiTe2 NWs and NiTe2 NFs were comparatively screened for hydrogen evolution reaction (HER) in extreme pH conditions, viz., 0 and 14. NiTe2 NWs delivered current densities of 10, 100, and 500 mA cm-2 at the overpotentials of 125 ± 10, 195 ± 4, and 275 ± 7 mV in 0.5 M H2SO4. Similarly, in 1 M KOH, overpotentials of 113 ± 5, 247 ± 5, and 436 ± 8 mV were required for the same current densities, respectively. On the other hand, NiTe2 NFs showed relatively poorer HER activity than NiTe2 NWs, which required overpotentials of 193 ± 7, 289 ± 5, and 494 ± 8 mV in 0.5 M H2SO4 for the current densities of 10 and 100 mA cm-2 and 157 ± 5 and 335 ± 6 mV in 1 M KOH for the current densities of 10 and 100 mA cm-2, respectively. Notably, NiTe2 NWs outperformed the state-of-the-art Pt/C 20 wt % loaded Ni foam electrode of comparable mass loading. The Pt/C 20 wt % loaded Ni foam electrode reached 500 mA cm-2 at 332 ± 5 mV, whereas NiTe2 NWs drove the same current density with 57 mV less. These encouraging findings emphasize that a NiTe2 NW could be an alternative to noble and expensive Pt as a nonprecious and high-performance HER electrode for proton-exchange membrane and alkaline water electrolyzers.