The inferior intrinsic performance of Ni-based catalysts for the hydrogen oxidation reaction (HOR) in an alkaline medium seriously restricts the utilization of emerging anion-exchange membrane fuel cells (AEMFCs). This is because the hydrogen and hydroxyl binding energies on Ni need to be optimized. Although electrocatalysts obtained by alloying Ni with Mo or W reportedly exhibit enhanced activity, they are still far from industrial requirements based on unbalanced HBE and OHBE. Herein, we report to further enhance alkaline HOR activity by constructing a heterostructure between NiW alloy and metal oxide (Ni17W3/WO2), which is synthesized through solvothermal treatment combined with annealing. The as-fabricated reduced graphene oxide (rGO)-supported Ni17W3/WO2 (Ni17W3/WO2/rGO) exhibits state-of-the-art catalytic activity (current density of 2.9 mA cm-2 at 0.1 V vs RHE), faster kinetics (geometric kinetics current density of 4.0 mA cm-2 that can be comparable to Pt/C), and high stability (maintaining the current density for more than 80 h) toward HOR in alkaline media. The detailed characterizations reveal that the charge transfer across the boundary arising from constructing the as-prepared heterostructure tunes the electronic structures, ultimately facilitating the HOR process.
Keywords: alkaline medium; anion exchange membrane fuel cells; heterostructure; hydrogen oxidation reaction; nonprecious metal electrocatalyst.