Chemical Structure of Fe–Ni Nanoparticles forEfficient Oxygen Evolution Reaction Electrocatalysis

摘要

Bimetallic iron–nickel-based nanocatalysts are perhaps the most active for the oxygen evolution reaction (OER) in alkaline electrolytes. Recent developments in literature have suggested that the ratio of iron and nickel in Fe–Ni thin films plays an essential role in the performance and stability of the catalysts. In this work, the metallic ratio of iron to nickel was tested in alloy bimetallic nanoparticles. Similar to thin films, nanoparticles with iron–nickel atomic compositions where the atomic iron percentage is ≤50% outperformed nanoparticles with iron–nickel ratios of >50%. Nanoparticles of Fe20Ni80, Fe50Ni50, and Fe80Ni20 compositions were evaluated and demonstrated to have overpotentials of 313, 327,, and 364 mV, respectively, at a current density of 10 mA/cm². While the Fe20Ni80 composition might be considered to have the best OER performance at low current densities, Fe50Ni50 was found to have the best current density performance at higher current densities, making this composition particularly relevant for electrolysis conditions. However, when stability was evaluated throughchronoamperometry and chronopotentiometry, the Fe80Ni20 composition resulted in the lowest degradation rates of2.9 μA/h and 17.2 μV/h, respectively. These results suggestthat nanoparticles with higher iron and lower nickel content, suchas the Fe80Ni20 composition, should be stilltaken into consideration while optimizing these bimetallic OER catalystsfor overall electrocatalytic performance. Characterization by electronmicroscopy, diffraction, and X-ray spectroscopy provides detailedchemical and structural information on as-synthesized nanoparticlematerials.