Spherical nickel doped cobalt phosphide as an anode catalyst for oxygen evolution reaction in alkaline media: From catalysis to system

Abstract

Anion exchange membrane water electrolysis (AEMWE) uses a zero-gap membrane-electrode-assembly (MEA) consisting of a polymer electrolyte membrane and non-precious metal-based catalysts. However, anode catalysts for the oxygen evolution reaction (OER), which is the rate-determining-step in WE, need to be intensively developed to achieve superior electrocatalytic activity and stability. Herein, we report the synthesis and characterization (experimental and simulation) of spherical Ni-doped (5–15 at%) cobalt phosphide (Ni-CoP) as the anode catalyst for the OER. Specifically, the DFT calculation exhibited that the addition of Ni in CoP might increase the energy density in the Fermi level of pristine CoP, enhance the charge transfer rate during the OER, and reduce the energy barrier for the formation of OOH* , thereby boosting the OER activity. The prepared Ni-doped CoP catalyst was directly loaded onto a foam-type Ni-based gas diffusion layer for effective application in AEMWE. It was found that the electrocatalytic activity of the AEMWE depends on the porosity of the NFs as catalyst substrates. The unit cell containing the membrane-electrode-assembly fabricated with NCP-10 delivered a high current density of 1.12 A cm−2 at 1.8 V and a low reduction rate of 0.64 mA cm−2 h−1 for 250 h.