In Situ Construction of Ni/Ni0.2Mo0.8N Heterostructure to Enhance the Alkaline Hydrogen Oxidation Reaction by Balancing the Binding of Intermediates

The inferior activity of hydrogen oxidation reaction (HOR) in alkali severely hampers the deployment of Ni catalysts in the promising anion exchange membrane fuel cells (AEMFCs), due to the unbalanced binding energies of hydrogen (HBE) and hydroxyl (OHBE) species. Ni-Mo alloy and nickel nitride have been proven to improve the Ni-based activities of HOR but they still can be further enhanced. Because it sacrifices the HBE for enlarging OHBE. Herein, it is reported that the activity can be further improved by constructing heterostructure between Ni nanoparticles (NPs) and nitride of Ni-Mo alloy (Ni0.2Mo0.8N) by an in situ synthetic strategy. The in situ prepared reduced graphene oxide (rGO) supported heterostructure (Ni/Ni0.2Mo0.8N/rGO) possesses the state-of-the-art activity (overpotential of 100 mV to achieve 2.9 mA cm(-2)), faster kinetics (kinetics current density of 11.20 mA cm(-2) and exchange current density of 2.74 mA cm(-2)), and ultrahigh durability (maintaining the current densities for over 40 h or 10000 cycles). Detailed characterizations together with density functional theory simulations reveal that the tuned d-band electronic structures optimize and balance the HBE and OHBE, facilitating the HOR process on the as-fabricated heterostructured catalyst.