Nanoporous Mo-Doped NiFe Oxide Nanowires from Eutectic Dealloying as an Active Electrocatalyst for the Alkaline Oxygen Evolution Reaction

Developing cost-effective, active, and robust oxygen evolution reaction (OER) electrocatalysts in alkaline electrolytes is a critical problem in the efficient conversion of renewable energy resources. Here, 3D bicontinuous Mo-doped nanoporous NiFe oxide nanowires (Ni1.4Fe1.7Mo0.05O4) fabricated by eutectic solidification and two-step dealloying exhibit an efficient electro-catalytic OER performance. The resultant nanoporous catalyst can achieve an exceptional activity with a low overpotential (205 mV at 10 mA cm-2) and a small Tafel slope (51.3 mV dec-1), outperforming most of the NiFe-based benchmarks. X-ray absorption spectroscopy combined with density functional theory calculations reveals that strong coupling between the Mo- Fe(Ni)-O sites and its remarkable lattice contraction facilitate the electron transfer on the tiny ligament surface, where the high-valent Mo sites can absorb H2O molecules and lower the energy barrier of OOH* for adsorption and activation of H2O. Meanwhile, 1-D nanowire and 3-D bicontinuous nanoporous structures together with the optimized atom ratio of Fe and Ni can accelerate electron/ion transport in the OER process, thus further enhancing the OER performance.