Activation of Lattice\nOxygen in Nitrogen-Doped High-Entropy\nOxide Nanosheets for Highly Efficient Oxygen Evolution Reaction

High-entropy oxides (HEOs) are potential electrocatalysts\nfor overcoming\nthe sluggish kinetics of the oxygen evolution reaction (OER). Conventionally,\nthe thermodynamic barrier of the lattice oxygen mechanism (LOM) is\nlower than that of the adsorbate evolution mechanism (AEM). However,\ncontrolling the transition from the AEM to the LOM remains challenging.\nHerein, an in situ modulation strategy has been developed to synthesize\nN-FeCoNiAlMoO<sub><i>x</i></sub> by introducing structural\ndirecting agents and electronic modulators. Different instruments\nwere used to identify the nitridation-triggered micromorphologies\nand phase transformations. X-ray photoelectron spectroscopy (XPS)\nand X-ray absorption fine structure spectroscopy (XAFS) reveal the\noptimized electronic structures after nitrogen doping. N-FeCoNiAlMo<sub><i>x</i></sub> exhibits OER performance with low overpotentials\nof 240 and 285 mV at 10 and 100 mA·cm<sup>–2</sup>, respectively.\npH dependence, free-radical capture experiments, and density functional\ntheory (DFT) calculations confirm that nitrogen doping facilitates\nthe LOM pathway. This work elucidates nitrogen’s critical role\nand the LOM pathway’s contribution to efficient OER performance.