Modification of NiCo-S with Phytate for Enhanced Electrocatalytic Hydrogen Evolution Activity

Abstract

Transition metal phosphides (TMP) are excellent non-precious metal electrocatalysts for hydrogen evolution reaction (HER). The generation of PO4 3− before and during the HER process may be inevitable due to the instability of TMP. To investigate the effect of PO4 3− on the HER catalytic activity of electrocatalysts in alkaline medium, NiCo-S nanotubes were modified with phytate (PHY) with six phosphate groups via adsorption. The successful modification was verified by zeta potential, FT-IR, element mapping, XPS, etc The NiCo-S/PHY displayed a higher HER activity than original NiCo-S. Under the optimum adsorption time (7 h), the overpotential at 10 mA cm−2 (η 10) of NiCo-S/PHY (173 mV) was only half that of the original NiCo-S (346 mV). The role of PO4 3− was discussed in detail. Moreover, this strategy was extended to NiCo-S grown directly on nickel foam (NiCo-S/NF) and the corresponding NiCo-S/PHY/NF also showed superior HER activity and good stability. This work provides a new strategy to improve the HER activity of electrocatalysts and also a novel perspective for the HER mechanism of TMP.