Iron Hydroxide-Modified Nickel Hydroxylphosphate Single-Wall Nanotubes as Efficient Electrocatalysts for Oxygen Evolution Reactions.

Development of efficient electrocatalysts for oxygen evolution reaction (OER) is of great significance for future renewable energy applications. Herein, efficient OER electrocatalysts based on iron hydroxide-modified nickel hydroxylphosphate (NiPO/Fe(OH) _x ) single-wall nanotubes (SWNTs) have been prepared by a facile stepwise surfactant-free solvothermal strategy, which possess diameters of about 6 nm and lengths of about several micrometers. Benefiting from the synergistic effect between iron hydroxides and NiPO SWNTs, the as-prepared NiPO/Fe(OH) _x SWNTs exhibit higher OER activity than primary NiPO SWNTs. Furthermore, the OER activity with different Fe contents displays a volcano-type shape, and the optimized NiPO/Fe(OH) _x SWNTs present excellent activity with a low overpotential of 248 mV to deliver a current density of 10 mA cm ^-2 and 323 mV to achieve a large current density of 100 mA cm ^-2 , as well as a remarkably low Tafel slope of 45.4 mV dec ^-1 in 1 M KOH electrolyte. The present work provides valuable insights to improve the OER performance by rational surface modification.