Roles of the self-reconstruction layer in the catalytic stability of a NiFeP catalyst during the oxygen evolution reaction

The roles of the self-reconstruction NiFe-OOH-P layer in the catalytic stability of the NiFeP catalyst during the oxygen evolution reaction (OER), especially in terms of the atomic dissolution and the adsorption behavior of formed bubbles, are seldom studied. Herein, through a systematic study on crystalline (Ni 1− x Fe x ) 3 P, a NiFeP catalyst, it was revealed that although Fe & P dissolve rapidly from the self-reconstruction layer, the self-reconstruction layer could suppress Fe & P dissolution from (Ni 1− x Fe x ) 3 P, tending to form a stable (Ni 1− x Fe x ) 3 P-O/NiOOH heterostructure. DFT simulations demonstrate that the synergistic effect between Fe-O of (Ni 1− x Fe x ) 3 P-O and NiOOH could still efficiently catalyze the OER. Thus, atomic dissolution does not obviously lower the activity. However, the self-reconstruction layer would change the original interface and increase the surface adsorbed bubbles, which determines the degradation of OER performance. Eventually, a superaerophobic heterostructure of (Ni 1− x Fe x ) 3 P/NiFe-OH-P is prepared by changing reconstruction conditions. The catalyst not only exhibits excellent activity with an overpotential of 233 mV at 10 mA cm −2 , but also obtains dramatically enhanced stability with a decrease in current density from 120 to 100 mA cm −2 after a 120 h potentiostatic test. Due to the synergistic effect between NiFeP and the self-reconstruction layer, the stability of a NiFeP catalyst during the oxygen evolution reaction is determined by the surface-adhesion O 2 bubbles rather than atomic dissolution.