Oxygen reduction reaction on Ni3(HITP)2: A catalytic site that leads to high activity

•A novel catalytic site for ORR is discovered on Ni3(HITP)2.•H2O2 is the primary production during ORR, which is consistent with the experimental observations.•Molecular dynamics simulations show that Ni3(HITP)2 has excellent thermodynamic stability.

As one kind of metal-organic frameworks (MOFs), Ni3(HITP)2 has recently been demonstrated to manifest high oxygen reduction reaction (ORR) performance due to its unique structure and property. However, the origin of the high activity of this experimentally synthesized material remains ambiguous. Herein, we performed detailed theoretical studies on the electrocatalytic ORR of the Ni3(HITP)2 monolayer. The calculated results uncover that, in addition to the traditional NiN catalytic site, the H atoms directly bonded to the N atoms can also act as the active site for ORR, with the activity even higher than that of NiN moiety. The relative energy diagrams show that the favorable ORR pathway on all possible active sites is the two-electron reduction mechanism from O2 to H2O2, which is well consistent with the experimental observations. Furthermore, the first-principles molecular dynamics simulations show that Ni3(HITP)2 also presents excellent thermodynamic stability.

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