Abstract:

Oxygen evolution reaction (OER) is the key reaction for water splitting, but its slow kinetics limitsits application. Therefore, rational design and construction of efficient OER catalysts are crucial for water splitting. Here, a Co²⁺ ion doped NiFe layered double hydroxides coupled Ti₆C_3.75 (NiFeCo-LDH-Ti₆C_3.75) catalyst was prepared by a simple one-step hydrothermal method using cobalt nitrate, nickel nitrate, iron nitrate, urea, and Ti₆C_3.75 as raw materials. NiFeCo-LDH-Ti₆C_3.75 catalyst showed a lamellar stacking structure, which is facilitating exposing more active sites. Introduction of Co²⁺ and Ti₆C_3.75 reduced the electronic density of Ni and Fe sites of NiFeCo-LDH-Ti₆C_3.75 catalyst. Benefiting from these features, the NiFeCo-LDH-Ti₆C_3.75 catalyst exhibits excellent OER activity with an overpotential of merely 290 mV at a current density of 20 mA·cm^-2 and a Tafel slope of 87.84 mV·dec^-1 with faster reaction kinetics. NiFeCo-LDH-Ti₆C_3.75 catalyst shows a relatively low charge transfer resistance, which means a fast charge transfer efficiency. Furthermore, after 6000 cycles of accelerated aging test at 20 mA·cm^-2, the overpotential only increased ~7 mV, indicating excellent cycle stability of NiFeCo-LDH-Ti₆C_3.75.

Key words: NiFe-LDH, Co doping, Ti₆C_3.75 doping